Various latest topics from “GMAT Club Forum”

Sum of Digits of Positive 2 two-digit number

aazhar — Sun, 27 May 2012 17:59:32 -0500

If the sum of the digits of the positive two-digit number x is 4, what is the value of x?

(1) x is odd.

(2) Twice the value of x is less than 44.

If a, b, c, d, and e are distinct odd integers, which of the

macjas — Sun, 27 May 2012 11:58:11 -0500

If a, b, c, d, and e are distinct odd integers, which of the five numbers is the median?

(1) a < b-c
(2) d > e

Tires of a certain brand, when purchased new, last for fou

macjas — Sun, 27 May 2012 11:56:31 -0500

Tires of a certain brand, when purchased new, last for four years. A customer can choose to purchase the new tires at a cost of $180 per tire or can have his current tires repaired at a cost of $40 per tire, a repair that will make the current tires last for one additional year. The average cost per year of the new tires is what percent greater than the cost of repairing the current tires?

A 8%
B 10%
C 12.5%
D 16.7%
E 25%

A certain bakery only sells bread. It sells bread at a regul

macjas — Sun, 27 May 2012 11:55:20 -0500

A certain bakery only sells bread. It sells bread at a regular price throughout the day, but decreases its price by y percent after 6 pm. Today, the bakery sold 300 loaves of bread. Did the bakery make more than $1450 today?

(1)y = 60

(2)Fully priced loaves of bread cost $12.50 each.

Bucket A is 1/4 full of sand, and Bucket B, which has one-ha

macjas — Sun, 27 May 2012 11:53:50 -0500

Bucket A is 1/4 full of sand, and Bucket B, which has one-half the capacity of Bucket A, is 3/8 full of sand. Jana pours the contents of Bucket B into Bucket A. Bucket A is now filled to what fraction of its capacity?

A 3/8
B 7/16
C 1/2
D 5/8
E 7/8

m and n are the x and y coordinates, respectively, of a poin

macjas — Sun, 27 May 2012 11:52:03 -0500

m and n are the x and y coordinates, respectively, of a point in the coordinate plane. If the points (m, n) and both lie on the line defined
by the equation , what is the value of p?

A 4/5
B 1
C 2
D 5
E 8

A certain protective additive increases from 45 days to 60 d

macjas — Sun, 27 May 2012 11:50:17 -0500

A certain protective additive increases from 45 days to 60 days the time between required maintenance checks on an industrial vehicle. By what percent is the time between maintenance checks increased by using the additive?

A 25%
B 33 1/3%
C 50%
D 66 2/3%
E 75%

Is 4^[x+1] > 5,000?

macjas — Sun, 27 May 2012 11:48:31 -0500

Is 4^[x+1] > 5,000?

1 4^[x+1]> 16,000

2 4^[x+1]= 4^x + 12,288

ABCDE is a regular pentagon with F at its center. How many d

macjas — Sun, 27 May 2012 11:43:21 -0500

Attachment:

Q19.gif

ABCDE is a regular pentagon with F at its center. How many different triangles can be formed by joining 3 of the points A, B, C, D, E and F?

A 10
B 15
C 20
D 25
E 30

In a certain playground, a square sand box rests in a circul

macjas — Sun, 27 May 2012 11:40:48 -0500

Attachment:

Q19.gif

In a certain playground, a square sand box rests in a circular plot of grass so that the corners of the sandbox just touch the edge of the plot of grass at points W, X, Y and Z, as shown. What is the distance from point W to point Y?

(1) The area of the circular plot is 49π
(2) The ratio of the area of the sand box to the area of the circular plot is 2/π.

If A and C are points in a plane, C is the center of circle

macjas — Sun, 27 May 2012 11:36:54 -0500

If A and C are points in a plane, C is the center of circle O, and the length of line segment AC is x, does point A lie outside circle O ?

(1) The circumference of circle O is xπ.

(2) The area of circle O is xπ.

If n ≠ 1, is (2xn - 2x)/(n-1) > y ?

macjas — Sun, 27 May 2012 11:35:31 -0500

If n ≠ 1, is (2xn - 2x)/(n-1) > y ?

1) x > y/2

2) n = 3

If @ represents one of the operations +, ×, or ÷, and p, q

macjas — Sun, 27 May 2012 11:33:34 -0500

If @ represents one of the operations +, ×, or ÷, and p, q, r, and s are real numbers, what is the value of (2 @ 3) @ (2 @ 3)?

(1) For some values of p, q, r, and s, (p + q) @ (r + s) ≠ (r + s) @ (p + q)

(2) (1 @ 2) @ (1 @ 2) = 1

What is the value of a − b ?

macjas — Sun, 27 May 2012 11:32:20 -0500

What is the value of a − b ?

(1) (10+a)/c = 1

(2) (15+b)/c = 1

A barrel contains only red balls, white balls, and brown bal

macjas — Sun, 27 May 2012 11:30:51 -0500

A barrel contains only red balls, white balls, and brown balls. If two balls are selected at random without replacing each ball, what is the probability that two brown balls will be selected?

1) The probability that one ball selected at random is either red or white is .

2) There are nine balls in the barrel.

Today a manufacturing company sold 200 units of a certain pr

macjas — Sun, 27 May 2012 11:29:03 -0500

Today a manufacturing company sold 200 units of a certain product. If on each of the next d days the company sells 70 units of the same product and the average daily sales of the product over the time period that includes today and the next d days is 80 units, what is the value of d ?

A 4
B 7
C 12
D 15
E 70

If n is a positive integer and if [m](n^3 - n)/(n+1) = 240[/

macjas — Sun, 27 May 2012 11:27:45 -0500

If n is a positive integer and if (n^3 - n)/(n+1) = 240, then what is the value of n?

A 12
B 16
C 17
D 20
E 48

If the average of the five numbers n, 2n – 4, 4n + 3, 5n +

macjas — Sun, 27 May 2012 11:24:31 -0500

If the average of the five numbers n, 2n – 4, 4n + 3, 5n + 2, and 6n + 5 is 52, what is the value of n ?

A 2 5/9
B 10
C 12
D 14 1/9
E 15

A number a is squared and then multiplied by negative 3. The

macjas — Sun, 27 May 2012 11:22:54 -0500

A number a is squared and then multiplied by negative 3. The result of this operation is equal to three times the sum of three times a and two. What is one possible value of a ?

A -3
B -2
C 1
D 2
E 3

If (18^a) * 9^(3a – 1)= (2^3)(3^b) and a and b are positive

macjas — Sun, 27 May 2012 11:21:47 -0500

If (18^a) * 9^(3a – 1)= (2^3)(3^b) and a and b are positive integers, what is the value of a?

A 22
B 11
C 9
D 6
E 3

What is the value of (4x-y) (1/3y)?

macjas — Sun, 27 May 2012 11:13:13 -0500

What is the value of (4x-y) (1/3y)?

(1) 4x = 3y

(2) 7x = 4

What is the value of x – y ?

macjas — Sun, 27 May 2012 11:11:48 -0500

What is the value of x – y ?

1)w + z = 7

2)wx – wy + xz – yz = 12

Two chefs, Chef Andrew and Chef Bonnie, were hired to prepar

macjas — Sun, 27 May 2012 11:10:36 -0500

Two chefs, Chef Andrew and Chef Bonnie, were hired to prepare a dinner. The two chefs began working at the same time, but Chef Andrew was only able to work for 2 hours. How many hours did it take Chef Bonnie, working alone, to finish making the dinner?

(1)Working alone, Chef Andrew made 1/4 of the meal.

(2)It would have taken 6 hours for Chef Bonnie to cook the entire meal herself.

A city council will select 2 of 9 available firefighters a

macjas — Sun, 27 May 2012 11:08:37 -0500

A city council will select 2 of 9 available firefighters and 1 of 6 available police officers to serve on an advisory panel. How many different groups of 3 could serve on the panel?

A 36
B 72
C 144
D 216
E 432

A soda can, in the shape of a right circular cylinder, is f

macjas — Sun, 27 May 2012 11:06:44 -0500

A soda can, in the shape of a right circular cylinder, is full of soda. If the volume of soda in the can is cubic inches and the diameter of the can is 8 inches, then what is the height, in inches, of the can?

A 1.5
B 3
C 4
D 4.5
E 6

In the rectangular coordinate system, if the line x = 2y + 5

macjas — Sun, 27 May 2012 11:05:26 -0500

In the rectangular coordinate system, if the line x = 2y + 5 passes through points (m,n) and (m + 2,n + p), what is the value of p ?

A. -2
B. 0
C. 1/2
D. 1
E. 2

|x|=|2y|, what is the value of x-2y?

kashishh — Sun, 27 May 2012 10:18:40 -0500

|x|=|2y|, what is the value of x-2y?

(1) x+2y = 6
(2) xy>0

i wish to have clarification on st. 1.
x+2y = 6
if x = 2, y = 2 or
if x= -2 , y = 4 then also it is '6'

do we need to keep the constraint +x = +2y while evaluating st.1 ?

An empty fuel tank with a capacity of 200 gallons was fill

macjas — Sun, 27 May 2012 06:59:43 -0500

An empty fuel tank with a capacity of 200 gallons was filled partially with fuel A and then to capacity with fuel B. Fuel A contains 12% ethanol by volume and fuel B contains 16% ethanol by volume. If the full fuel tank contains 30 gallons of ethanol, how many gallons of fuel A were added?

A 160
B 150
C 100
D 80
E 50

Both Betty and Wilma earn annual salaries of more than 50,00

mokap25 — Sun, 27 May 2012 05:20:41 -0500

Both Betty and Wilma earn annual salaries of more than 50,000. Is Wilma's annual salary greater than 50,000?

(1) Betty annual salary is closer to 50,000 than Wilma's is.

(2) Betty's annual salary is closer to 35,000 than it is to WIlma's annual salary.

Can anyone help solve, using the modulus distance approach would be even better.

OA is

[Reveal] Spoiler:

At a certain resort, each of the 39 food service employees

vibhav — Sun, 27 May 2012 00:27:27 -0500

At a certain resort, each of the 39 food service employees is trained to work in a minimum of 1 restaurant and a maximum of 3 restaurants. The 3 restaurants are the family buffet, the dining room, and the snack bar. Exactly 19 employees are trained to work in the family buffet, 18 are trained to work in the dining room, and 12 are trained to work in the snack bar. If 4 employees are trained to work in exactly 2 restaurants, how many employees are trained to work in all 3 restaurants?

A. 2
B. 3
C. 4
D. 5
E. 6

A three-person committee must be chosen from a group of 7

anujkch — Sat, 26 May 2012 13:58:34 -0500

Hi All,

Need help to understand what is wrong with my approach.

A three-person committee must be chosen from a group of 7 professors and 10 graduate students. If at least one of the people on the committee must be a professor, how many different groups of people could be chosen for the committee?

A. 70
B. 560
C. 630
D. 1,260
E. 1,980

My approach :-
There are 3 seats. One has to be a professor. The remaining can be occupied by remaining professors or students.

Thus ways of filling seat 1 is 7 (You have to pick one professor out of 7)
Ways of filling remaining 2 seats will be to pick 2 out of 16 (10 S and 6 P as one P has already been picked. ) i.e. C(16,2) = 16*15/2 = 120

Total 120* 7 = 840

I know something is wrong with this approach but what exactly am I missing.

If x and y are integers, does (x)^y * (y)^-x = 1?

kunalbh19 — Sat, 26 May 2012 07:59:57 -0500

If x and y are integers, does (x)^y * (y)^-x = 1?

(1) (x)^x > y
(2) x > (y)^y

I think it should be E! Please any suggestions on how to solve this..

If x and y are non-zero integers, and 9x^4 – 4y^4 = 3x^2 + 2

manimgoindowndown — Fri, 25 May 2012 17:14:43 -0500

If x and y are non-zero integers, and 9x^4 – 4y^4 = 3x^2 + 2y^2, which of the following could be the value of x2 in terms of y?

A. 4y^2/3
B. 2y^2
C. (2y^2+1)/3
D. 2y^2
E. 6y^2/3

When a problem involves variables raised to the fourth power, it is often useful to represent them as a square of another square, since this approach will allow us to apply manipulations of squares. Also note that since we are dealing with high exponents, the approach of plugging numbers would prove time-consuming and prone to error in this case.

9x4 – 4y4 = (3x2)2 – (2y2)2 = (3x2 + 2y2)(3x2 – 2y2).

(3x2 + 2y2)(3x2 – 2y2) = (3x2 + 2y2)

I'm not getting how (3x2 + 2y2)(3x2 – 2y2) = (3x2 + 2y2). Can someone please explain?

Another Cards Problem

sinclairv — Fri, 25 May 2012 15:19:20 -0500

I take advantage of this first post to say hi to the GMAT Club which I find very interesting and useful.

I experience some difficulties with a simple probability problem found in the book "Conquering GMAT Math and Integrated Reasoning":

"What is the probability that a card selected at random from a standard deck of playing cards will be a 7 or a club ?"

It's a example to illustrate some theory so there is no multiple choice but the answer is:
"There are 52 cards in a deck. There are 13 each in hearts, clubs, spades, and diamonds. There are four 7s, one each in hearths, clubs, spades, and diamonds. Thus the 7 of clubs is counted twice , once as a club and once as a 7 There are 13 clubs plus tree 7s that are not clubs.
P(7 or Club) = 16/52 = 4/13

My problem with this answer is actually the fact that this 7 of clubs isn't counted twice as announced : why doesn't this card count as a double chance of getting an expected card (7 or club) ?
My natural answer would have been P= (13+4)/52 = 17/52

Thank by advance

Quantitative Performance - Need Advise, Weird Question

htbreme — Fri, 25 May 2012 11:49:07 -0500

Hi everyone!
I have a relatively weird question.
I've been studying for my GMAT for about 5 months now. I gave the exam a month a go and scored a 690 (Q44, V40). Although I reached the exam with a heavy burn out due to 12 hour days at work + 2 hours of GMAT and 9 hour GMAT sessions during both days of the weekend this score was a deception (specially math) since I know I have the knowledge to do a lot better and I'm doing a lot of unnecessary errors in the math section.

The thing is that after this and after an additional month of hard study, I still have not being able to lower my quant error below 12 per test. By re doing every wrong question and seeing that I know the content and I have very little knowledge questions I'm starting to think I have an "attitudinal" problem. At first I though that the error where a result of me getting very tense during the practice exams, but I think I managed to relax little bit more and the error ares still there.

This is getting quite frustrating as I think there nothing worse than knowing you can give a really good exam and not being able to do it when it counts

Has anyone experienced this? How did you deal with it? How did you conquer this trap?

Thanks in advance for the help

Best

If -1< x <0 or x >1 then which of the following must be true

Joy111 — Fri, 25 May 2012 09:56:17 -0500

If -1< x <0 or x >1 then which of the following must be true about x :

1). |x|>-1
2). x>-1
3). x>1

A. None
B. 1 only
C. 2 only
D. 1 and 2
E. 1,2 and 3

can anybody check this question and tell me , why the answer cannot be D.

statement 2) I know is correct but I think 1) is also correct , can anyone show me why 1) cannot be true

If n is a positive integer, is n^2 - 1 divisible by 24?

kunalbh19 — Fri, 25 May 2012 04:00:23 -0500

If n is a positive integer, is n^2 - 1 divisible by 24?

(1) n is a prime number.
(2) n is greater than 191

A zinc-copper alloy with 3 kg of pure zinc would contain 90%

sid1599 — Fri, 25 May 2012 03:20:45 -0500

A zinc-copper alloy with 3 kg of pure zinc would contain 90% of zinc. The alloy with 2 kg of 90% zinc alloy contains 84% of zinc. Calculate the weight and percentage of zinc in the zinc-copper alloy.

A. 2.4 kg or 80%
B. 1.4 kg or 88%
C. 3.4 kg or 60%
D. 7.4 kg or 18%
E. 1.4 kg or 60%

On a certain day, orangeade was made by mixing a certain

macjas — Fri, 25 May 2012 01:32:13 -0500

On a certain day, orangeade was made by mixing a certain amount of orange juice with an equal amount of water. On the next day, orangeade was made by mixing the same amount of orange juice with twice the amount of water. On both days, all the orangeade that was made was sold. If the revenue from selling the orangeade was the same for both days and if the orangeade was sold at $0.60 per glass on the first day, what was the price per glass on the second day?

A. $0.15
B. $0.20
C. $0.30
D. $0.40
E. $0.45

The total cost of 100 paper plates and 200 paper cups is $5.

jsphcal — Thu, 24 May 2012 23:59:44 -0500

The total cost of 100 paper plates and 200 paper cups is $5.00 At the same rates what is the total cost of 20 of the plates and 40 of the cups?

A. $.90
B. $1.00
C. $1.20
D. $1.50
E. $1.60

I know i will have 2 equations equations

100p + 200c = $5.00
20p + 40c = ?

i tried dividing the first equation by 100 which would give me

1p+2c = .05
if i subtract 2c then

1p = .05-2c

i could plug this back in ans solve for "p" but i think there is a much faster way to solve these types of equations.

What is the value of |x| ?

sandal85 — Thu, 24 May 2012 23:24:46 -0500

What is the value of |x| ?

(1) x = –|x|
(2) x^2 = 4

When is the mean = median?

bellcurve — Thu, 24 May 2012 15:04:32 -0500

From my understanding, mean = median if,
1. the set consists of evenly spaced numbers
2. if all the members of the set are equal
3. set has just one number

Is there any thing else? In DS type of "is mean = median" questions, what do you have to know to be sure that mean = median?

Is a even?

cyberjadugar — Thu, 24 May 2012 05:38:19 -0500

Is a even?

(1) 2a is even.
(2) \sqrt{a} is even.

[Reveal] Spoiler: Solution

1) a can be fraction.
2) a can be irrational (\sqrt{2}..etc.)

Gambling with 4 dice, what is the probability of getting an

cyberjadugar — Thu, 24 May 2012 03:31:03 -0500

Gambling with 4 dice, what is the probability of getting an even sum?

A. 3/4
B. 1/2
C. 2/3
D. 1/4
E. 1/3

Looking for a one-liner answer...

If r > s + t , is r positive? (1) s > t (2) r/(s+t) > 1

kuttingchai — Wed, 23 May 2012 22:59:35 -0500

If r > s + t , is r positive?

(1) s > t
(2) r/(s+t) > 1

not sure why the answer in book is "B"

In a neighborhood having 90 households, 11 did not have

navigator123 — Wed, 23 May 2012 14:24:46 -0500

In a neighborhood having 90 households, 11 did not have either a car or a bike. If 12 households had a both a car and a bike and 44 had a car, how many had bike only?

A. 30
B. 35
C. 20
D. 18
E. 10

If x and y are integers and 4xy = x^2*y+4y, what is the

kashishh — Wed, 23 May 2012 03:57:56 -0500

If x and y are integers and 4xy = x^2*y+4y, what is the value of xy?

(1) y-x = 2
(2) x^3 <0

what I did : 4xy = x^2y+4y
4x = x^2+4
x^2-4x+4 = 0
(x-2)^2=0
x = 2
is this wrong?

Is x^2 > 15? (1) x > -4 (2) x^3 < 0

carcass — Tue, 22 May 2012 16:51:27 -0500

Is x^2 > 15?

(1) x > -4
(2) x^3 < 0

To which angel does the Expression Angel BDO refer?

LasseSchmid — Tue, 22 May 2012 14:46:22 -0500

Hi,

I don't understand to which angel the expression angel BDO in a triangle refers? Is it the angelt at B, D or O? It cannot be to the triangle itself because then it would always be 180 degree or not?

Sorry for that stupid question.

Best,

Is xy= -1? (1) x=y (2) y=1

BDSunDevil — Tue, 22 May 2012 12:50:33 -0500

Is xy= -1?

(1) x=y
(2) y=1

How many four-digit positive integers can be formed by using

gmihir — Tue, 22 May 2012 11:35:05 -0500

How many four-digit positive integers can be formed by using the digits from 1 to 9 so that two digits are equal to each other and the remaining two are also equal to each other but different from the other two ?

A. 400
B. 1728
C. 108
D. 216
E. 432

I am getting answer as 432, but the OA is D. Here is the approach I used.

First number can be selected from 1 to 9 - in 9 ways, 2nd number has to be same as the one selected so only 1 way, Third number can be selected from remaining 8 numbers in 8 ways and 4th number again has to be only 1
so in total (9*1*8*1)*4!/2!*2! = 72*6 = 432 Can anyone please explain what mistake I am making here? Thanks!

A special sequence of numbers is written as 2, 9, 28, 65, 12

gmihir — Tue, 22 May 2012 11:16:14 -0500

A special sequence of numbers is written as 2, 9, 28, 65, 126 …….Find the ratio of the 7th term to the 15th term.

A. 1/4
B. 1/2
C. 129/422
D. 43/422
E. 43/129

couldn't get the logic behind the terms in the sequence

Is x + y – z + t even?

gmihir — Tue, 22 May 2012 11:12:15 -0500

Is x + y – z + t even?

(1) x + y + t is even
(2) tz is odd

why the answer is not C? as tz is odd, t and z both must be odd and and as x+y+t is even, even - odd = odd so C, can anyone please explain?

What is the maximum possible area of triangle?

Smita04 — Mon, 21 May 2012 22:33:28 -0500

What is the maximum possible area of triangle?

(1) Two sides of the triangle are 7 cm and 14 cm.
(2) The triangle is inscribed in a circle and one of its sides is 7 cm.

In the well-known Thanksgiving equation below, M = the

carcass — Mon, 21 May 2012 19:06:43 -0500

In the well-known Thanksgiving equation below, M = the number of minutes after dinner until a person falls asleep, t = the ounces of turkey consumed by that person, s = the ounces of stuffing consumed by that person, c = the number of cocktails consumed by that person, v = the ounces of total vegetables consumed by that person, and K is a constant. Last year, Aunt Jane fell asleep exactly 17 minutes after dinner and she consumed 8 ounces of turkey, 6 ounces of stuffing, 5 cocktails, and 10 ounces of vegetables. This year Lauren is planning on eating 10 ounces of turkey, 6 ounces of stuffing, and 14 ounces of vegetables, while drinking 7 cocktails.

M=\frac{2^{t+s}+4^c}{K^v}

If Lauren sticks to her plan, how many minutes after dinner will Lauren fall asleep?

A. 1
B. 2
C. 5
D. 20
E. It cannot be determined from the information given

Is not enormously tough but due to bunch of numbers you should be careful.

Is AD the bisector of angle A in triangle ABC?

vibhav — Mon, 21 May 2012 12:36:09 -0500

Is AD the bisector of angle A in triangle ABC?

(1) Triangle ABD and triangle ACD have equal areas
(2) AD is not perpendicular to BC

Guys any idea how to solve this question?

Which values of x are solutions |x + 1| + |x - 1| <= 2

sandal85 — Mon, 21 May 2012 11:14:24 -0500

Which values of x are solutions to the inequality |x + 1| + |x - 1| <= 2 ?
Apart from algebra can we think conceptually to solve this

At a certain high school, the junior class is twice the size

kashishh — Mon, 21 May 2012 07:29:49 -0500

At a certain high school, the junior class is twice the size of the senior class. If 1/3 of the seniors & 1/4 of the juniors study Japanese, what fraction of the students in both classes do not study Japanese?

A. 1/6
B. 5/18
C. 5/12
D. 7/12
E. 13/18

Is it possible to do as follows?
1/3*s+1/4*2s = study japanese
then 5/6 * s = study japanese and 1/6 do not
why is this wrong?

If M is a sequence of consecutive integers which contains

Smita04 — Mon, 21 May 2012 00:49:17 -0500

If M is a sequence of consecutive integers which contains more than 11 terms, what is the average of M?

(1) In M, the number of terms that are less than 10 is equal to the number of terms greater than 21.
(2) There are 20 terms in M.

If sets A and B have the same number of terms, is the

Smita04 — Mon, 21 May 2012 00:48:20 -0500

If sets A and B have the same number of terms, is the standard deviation of set A greater than the standard deviation of set B?

(1) The range of set A is greater than the range of set B.
(2) Sets A and B are both evenly spaced sets.