Solving GRE math and analytical problems

Game Gems

noreply@blogger.com (Alexey Izvalov) — Sat, 20 Aug 2011 19:22:00 +0000

There are the real gems among the flash games. You can play great free online games, read their reviews and wathc walkthroughs on my new site GameGems.org. Welcome!

Smart Flash Games

noreply@blogger.com (Alexey Izvalov) — Sun, 17 Jul 2011 08:02:00 +0000

The whole first half of 2011 I was involved in the creation of interesting flash games. So, I uploaded them to the web and created my portfolio blog, where you can play them and have fun. The games, besides being entertaining, hepl the players train their memory, attention and reaction, which is significant for successful GRE exams.

Welcome to Smart Flash Games!
Sky Control

5 Brain Teasers

I Wanna Win!

GRE Math Problem 78

noreply@blogger.com (Alexey Izvalov) — Sat, 10 Jul 2010 10:47:00 +0000

In the preceding figure, if l₁||l₂, what is the value of x?

(A) 36 (B)54 (C)90 (D)144 (E) 154

Solution for GRE Math Problem 77:
As the angle between the base of the triangle and the vertical line is not marked, the relation between x and y could be of any value. Answer:D

GRE Math Problem 77

noreply@blogger.com (Alexey Izvalov) — Wed, 26 May 2010 06:23:00 +0000

Compare two values:

Column A	Column B
x	y

Solution for GRE Math Problem 76:

The value of this angle can be found as the sum of the angles a and b. As 20 minutes is 1 third of an hour, angle a is one third of 360 degrees, and equals to 120 degrees.
Then, angle b is two thirds of and angle between "11" and "12", then, it is two thirds of 30 degrees, which equals to 20 degrees.
Total 120+20=140 degrees
Answer: C

GRE Math Problem 76

noreply@blogger.com (Alexey Izvalov) — Thu, 13 May 2010 12:06:00 +0000

Compare two values:

Column A	Column B
The measure, in degrees, of the smaller angle formed by the hour hand and the minute hand of a clock at 11:20	140

Solution for GRE Math Problem 75:

As he made a 25% profit on one painting, he sold it for 125% of the original price.
$2000=125%
$1600=100% - its original price was $1600

As he had a 25% loss on the second painting, he sold it for 75% of the original price.

$2000=75%
$2666.(6)=100% - its original price was $2666.(6)

Last year Leo paid for both paintings $1600+$2666.(6)=$4266 and this year he got $4000 for selling them. So, he lost more than $100

Answer:(C) He lost more than $100.

GRE Math Problem 75

noreply@blogger.com (Alexey Izvalov) — Thu, 06 May 2010 14:13:00 +0000

Last year Leo bought two paintings. This year he sold them for ">2000 each. On one, he made a 25% profit, and on the other he had a 25% loss. What was his net loss or profit?
(A) He broke even.
(B) He lost less than $100.
(C) He lost more than "$100.
(D) He earned less than $100.
(E) He earned more than $100.

Solution for GRE Math Problem 74:
By what fraction is greater than ?

So, of the number is 7. Therefore, the whole number is 12.

But we were asked about the of this number, so, the answer is 12*3/5=20. Thank you for pointing this in comment :)

Answer:(D)20

GRE Math Problem 74

noreply@blogger.com (Alexey Izvalov) — Tue, 04 May 2010 14:11:00 +0000

If of a number is 7 more then of the number. What is of the number?
(A) 12
(B) 15
(C) 18
(D) 20
(E) 24

Solution for GRE Math Problem 73:
In order to determine the total number of players we have to multiply the number of players in one team by the number of teams in one division by the number of divisions. We’ll get dtp
Answer: (B) dtp

GRE Math Problem 73

noreply@blogger.com (Alexey Izvalov) — Sun, 02 May 2010 14:07:00 +0000

The Center City Little League is divided into d divisions. Each division has t teams, and each team has p players. How many players are there in the entire league?
(A) d+t+p
(B) dtp
(C)
(D)
(E)

Solution for GRE Math Problem 72:
All the positive multiples of 5 less than 26 are: 5, 10, 15, 20, 25. Their average will be: =1+2+3+4+5=15
All the positive multiples of 7 less than 26 are: 7, 14, 21. Their average will be: =14
Answer:A

GRE Math Problem 72

noreply@blogger.com (Alexey Izvalov) — Fri, 30 Apr 2010 14:05:00 +0000

Compare two values:

Column A	Column B
The average (arithmetic mean) of all the positive multiples of 5 less than 26	The average (arithmetic mea: of all the positive multiples of 7 less than 26

Solution for Questions GRE Analytical Problem 5, Part 2

noreply@blogger.com (Alexey Izvalov) — Tue, 27 Apr 2010 08:28:00 +0000

Question IV

If S appears on a panel, that panel must consist of at least how many professors?

(A) 3

(B) 4

(D) 6

(E) 7

C6: S => (NV)

And there are no more conditions that require more members.

Answer (A) 3

Question V

Which of the following is an acceptable group of professors for a panel?

(A) M, N, Q, R – violates C2: !(MNR)

(B) M, Q, R,T – is quite acceptable

(D) M, S, U, V – violates C6: S => (NV)

(E) N,R,T,U – violates C5: R <=> Q

Answer (A) M, N, Q, R

Question VI

Which of the following groups of professors can form an acceptable panel by doing nothing more than adding one more professor to the group?

(A) M, R, T

C5:R <=> Q

We must add Q and we’ll get an acceptable panel

(B) N,Q,M

C5:R <=> Q

We must add R/ But that panel would violate

C2: !(MNR)

According to

C6: S => (NV)

We must add both N and V

(D) Q,R,V

C4: V=>(MS) or (MU) or (SU) or (MSU)

We must add at least two members

(E) V, R, N

C4: V=>(MS) or (MU) or (SU) or (MSU)

We must add at least two members

Answer (A) M, R, T

Question VII

Of the group N, S, T, U, V, which professor will have to be removed to form an acceptable panel?

(A) N

(B) S

(D) U

(E) V

This panel violates

C1:!(NTU)

So, we must remove one of them.

But the presence of N and V is required by S

C6: S => (NV)

Then, we must remove T

Answer (C) T

Solution for Questions GRE Analytical Problem 5, Part 1

noreply@blogger.com (Alexey Izvalov) — Mon, 26 Apr 2010 08:28:00 +0000

Solution for Questions GRE Analytical Problem 5:

Let’s fix the conditions:

C1: N, T, and U cannot all appear on the same panel.

!(NTU)

In another form it can be written:

(NT)=>!V

(NU)=>!T

(TU)=>!N

C2: M. N, and R cannot all appear on the same panel.

!(MNR)

In another form it can be written:

(MN)=>!R

(MR)=>!N

(NR)=>!M

C3: Q and V cannot appear on the same panel.

!(QV)

In another form it can be written:

Q <=> !V

V <=> !Q

C4: If V appears on a panel, at least two professors of the trio M, S, and U must also appear on the panel.

V=>(MS) or (MU) or (SU) or (MSU)

Or, equivalent to this:

(!M!S) or (!M!U) or (!S!U)=>!V

C5: Neither R nor Q can appear on a panel unless the other also appears on the panel.

R <=> Q

From this follows:

!R <=> !Q

C6: If S appears on a panel, both N and V must also appear on that panel.

S => (NV)

Then,

!N or !V => !S

Now we can proceed to question solving.

Question I

Which of the following CANNOT appear on a panel with R?

(A) M

(B) N

(D) S

(E) T

C5: R <=> Q

C4: Q <=> !V

C6: !N or !V => !S

So, professor S CANNOT appear on a panel with R

Answer (D) S

Question II

Exactly how many of the professors can appear on a panel alone?

(A) 1

(B) 2

(D) 4

(E) 5

C4: V=>(MS) or (MU) or (SU) or (MSU)

Professor V can’t appear on a panel alone.

C5: R <=> Q

Professor’s R and Q can’t appear on a panel alone.

C6: S => (NV)

Professor S can’t appear on a panel alone.

So, only four of them can.

Answer (D) 4

Question III

If neither V nor N appears on a panel, then which of the following must be true?

(A) M appears on the panel.

(B) Q appears on the panel.

(D) S does not appear on the panel.

(E) U does not appear on the panel.

C6: !N or !V => !S

Answer (D) S does not appear on the panel.

Analytical Problem 5

noreply@blogger.com (Alexey Izvalov) — Mon, 19 Apr 2010 14:23:00 +0000

The planning committee of an academic conference is planning a series of panels using eight professors, M, N, Q, R, S, T, U, and V. Each panel must be put together in accordance with the following conditions:

N, T, and U cannot all appear on the same panel.

M. N, and R cannot all appear on the same panel.

Q and V cannot appear on the same panel.

If V appears on a panel, at least two professors of the trio M, S, and U must also appear on the panel.

Neither R nor Q can appear on a panel unless the other also appears on the panel.

If S appears on a panel, both N and V must also appear on that panel.

Question I

Which of the following CANNOT appear on a panel with R?

(A) M

(B) N

(D) S

(E) T

Question II

Exactly how many of the professors can appear on a panel alone?

(A) 1

(B) 2

(D) 4

(E) 5

Question III

If neither V nor N appears on a panel, then which of the following must be true?

(A) M appears on the panel.

(B) Q appears on the panel.

(D) S does not appear on the panel.

(E) U does not appear on the panel.

Question IV

If S appears on a panel, that panel must consist of at least how many professors?

(A) 3

(B) 4

(D) 6

(E) 7

Question V

Which of the following is an acceptable group of professors for a panel?

(A) M, N, Q, R

(B) M, Q, R,T

(D) M, S, U, V

(E) N,R,T,U

Question VI

Which of the following groups of professors can form an acceptable panel by doing nothing more than adding one more professor to the group?

(A) M, R, T

(B) N,Q,M

(D) Q,R,V

(E) V, R, N

Question VII

Of the group N, S, T, U, V, which professor will have to be removed to form an acceptable panel?

(A) N

(B) S

(D) U

(E) V

Solution for GRE Math Problem 71:

Peter's grade > Victor's grade

Georgette’s grade > Victor's grade

We can’t determine, which of these grades is higher

Answer:D

GRE Math Problem 71

noreply@blogger.com (Alexey Izvalov) — Tue, 13 Apr 2010 19:07:00 +0000

Peter's grade was higher than that of Victor.and Victor's grade was less than that of Georgette.

Column A	Column B
Georgette's grade	Peter's grade

Solution for GRE Math Problem 70:

Area=length x width

New Area=length x (1.25 width) = 1.25 (length x width) = 1.25 Area

Area will increase by 25%.

Answer:(A) 25%

GRE Math Problem 70

noreply@blogger.com (Alexey Izvalov) — Mon, 12 Apr 2010 19:06:00 +0000

If the width of a rectangle is increased by 25% while the length remains constant, the resulting area is what percent of the original area?

(A) 25%

(B)75%

(D)225%

(E) Cannot be determined from the information given.

Solution for GRE Math Problem 69:

At what rate is the water filling the tank?
800-300=500 cubic feet
How many minutes will it take to completely fill a water tank?
3,750:500 = 7.5 minutes = 7 min. 30 sec.

Answer:(C) 7 min. 30 sec.

GRE Math Problem 69

noreply@blogger.com (Alexey Izvalov) — Sun, 11 Apr 2010 19:04:00 +0000

How many minutes will it take to completely fill a water tank with a capacity of 3,750 cubic feet if the water is being pumped into the tank at the rate of 800 cubic feet per minute and is being drained out of the tank at the rate of 300 cubic feet per minute?
(A) 3 min. 36 sec.
(B) 6 minutes
(C) 7 min. 30 sec.
(D) 8 minutes
(E) 1,875 minutes

Solution for GRE Math Problem 68:

The legs of triangle BCE equal to the sides of the square ABCD. So, its area is the half of the area of ABCD. Thus, the area of ABCD is 16

Answer:(C) 16

GRE Math Problem 68

noreply@blogger.com (Alexey Izvalov) — Sat, 10 Apr 2010 19:01:00 +0000

If the area of the triangle BCE is 8, what is the area of the square ABCD?
(A) 4
(B) 8
(C) 16
(D) 22
(E) 82

Solution for GRE Math Problem 67:
As and , then PQRS is a parallelogram. And as PQ=QR, it is a rhomb. Its obtuse angle equals 120 degrees, and the acute angle is 60 degrees. Then, triangle PQR is equilateral and PQ=QR=QP=3
Answer: (C) 3

GRE Math Problem 67

noreply@blogger.com (Alexey Izvalov) — Fri, 09 Apr 2010 18:58:00 +0000

Here and .
If PQ=3 and QR=3, then what is the length of PR?
(A)
(B)
(C) 3
(D)
(E)

Solution for GRE Math Problem 66:
As the y-coordinates of A and B are equal, the distance between them is 2-(-4)=6. That’ll be the diameter of the circle. The radius of the circle is 3. Its area will be
Answer:(C) 9

GRE Math Problem 66

noreply@blogger.com (Alexey Izvalov) — Thu, 08 Apr 2010 18:53:00 +0000

If A is the point (-4, 1) and B is the point (2, 1), what is the area of the circle which has AB as a diameter?
(A) 3
(B) 6
(C) 9
(D) 12
(E) 36

Solution for GRE Math Problem 65:

1 < ab < 2
2 < a+b < 4

So, ab < 2 < a+b

Answer:B

GRE Math Problem 65

noreply@blogger.com (Alexey Izvalov) — Wed, 07 Apr 2010 18:04:00 +0000

a < b

Column A	Column B
ab	a+b

Solution for GRE Math Problem 64:

As we can see, the circle whose diameter is a is located within the square whose side is a for any value of a. So, the square’s area is greater.

Answer: A

GRE Math Problem 64

noreply@blogger.com (Alexey Izvalov) — Tue, 06 Apr 2010 17:59:00 +0000

a<1

Column A	Column B
The area of a square whose side is a	The area of a circle whose diameter is a

Solution for GRE Math Problem 63:
As

then

Let’s find the difference

Then c

Answer:B

GRE Math Problem 63

noreply@blogger.com (Alexey Izvalov) — Mon, 05 Apr 2010 17:56:00 +0000

c and d are positive

Column A	Column B
c	d

Solution for GRE Math Problem 62:
Point (a,b) lays in the quarter where x<0 and y>0. So, a<0 and b>0 and b>a
Answer:B

GRE Math Problem 62

noreply@blogger.com (Alexey Izvalov) — Sun, 04 Apr 2010 17:08:00 +0000

Column A	Column B
a	b

Solution for GRE Math Problem 61:
326(31)-326(19) =326(31-19)=326(12) – here we need not make any calculations, because there is only one answer which is more than 10 times greater than 326

Answer:(A)3,912

GRE Math Problem 61

noreply@blogger.com (Alexey Izvalov) — Sat, 03 Apr 2010 17:05:00 +0000

326(31)-326(19) =

(A)3,912

(B)704

(D)326

(E)10

Solution for GRE Math Problem 60:
for x>0
Answer:B

GRE Math Problem 60

noreply@blogger.com (Alexey Izvalov) — Fri, 02 Apr 2010 17:02:00 +0000

x>0

Column A	Column B

Solution for GRE Math Problem 59:

The perimeter of the square is
Answer:(C) 3x + 4

GRE Math Problem 59

noreply@blogger.com (Alexey Izvalov) — Thu, 01 Apr 2010 16:57:00 +0000

The length of each side of a square is
What is the perimeter of the square?
(A) x + 1
(B) 3x + 1
(C) 3x + 4
(D)
(E) It cannot be determined from the information given.

Solution for GRE Math Problem 58:

How much, in dollars, will receive the second one?
240-180 = 60

What is the difference between the amounts received by the two persons?
180-60=120

Answer: (C)$120