Showing posts with label geomery. Show all posts
Showing posts with label geomery. Show all posts

Monday, April 12, 2010

GRE Math Problem 70

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% 
(C) 125% 
(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.

Friday, April 9, 2010

GRE Math Problem 67



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

Thursday, March 25, 2010

GRE Math Problem 52

A rectangular rug covers half of a rectangular floor that is 9 feet wide and 12 feet long. If the dimensions of the rug are in the same ratio as those of the floor, how many feet long is the rug?
(A) 6
(B)
(C)
(D)
(E)


Solution for GRE Analytical Problem 4:
Let’s arrange data and write down requirements and restrictions
  • One piece is purple and two pieces each are red, green, yellow, and blue.
We have the colours of P, R, R, G, G, Y, Y, B, B,
  • The two red pieces are consecutive numbers.
Requirement 1: R-R
  • The number 4 is green.
Requirement 2: 4G
  • The two blue pieces are not consecutive numbers.
Restriction 1: NOT B-B
  • Both the 1 and the 9 are yellow.
Requirement 3: 1Y
Requirement 4: 9Y
  • The purple piece is not a number immediately greater than or less than either green piece.
Restriction 2: NOT G-P
Restriction 3: NOT P-G
And we can fill in the table using the requirements 2, 3, 4:
1 2 3 4 5 6 7 8 9
Y G Y
Then, using the Restrictions 2 and 3, we can say that neither 3, nor 5 can be Purple.

Question I. If one of the red pieces is the number 3, what number is the other red piece?
1 2 3 4 5 6 7 8 9
Y R G Y
According to Requirement 1: R-R, number 2 must be Red.
Answer: (A) 2

Question II. If the number 5 is green, each of the following could be true EXCEPT
1 2 3 4 5 6 7 8 9
Y G G Y
Answer: (B) The number 6 is purple. – This statement contradicts Restriction 2: NOT G-P

Question III. If the number 6 is green, which of the following could be true?
1 2 3 4 5 6 7 8 9
Y G G Y
If 6G, we’ll have only two places for the Purple piece: 2 or 8 . If 2P, then we’ll have two consecutive slots for R-R, it is 7-8. Two remaining slots will be taken by the Blue pieces
1 2 3 4 5 6 7 8 9
Y P B G B G R R Y
If 8G, we’ll have only two places for the Purple piece. If 2P, then the two consecutive slots for R-R are 2-3. Two remaining slots will be taken by the Blue pieces
1 2 3 4 5 6 7 8 9
Y R R G B G B P Y
Now let’s look trough the answers
(A) The number 2 is blue. - impossible
(B) The number 3 is purple. - impossible
(C) The number 5 is red. - impossible
(D)The number 5 is purple. - impossible
(E) The number 7 is blue. – possible within the second arrangement
Answer: (C) The number 5 is red (Thanks to swath for correction).

Question IV. Which of the following, if true, would enable you to determine the color of every number?
Let’s first find the statement, which involves the color and location with more restrictions. Let’s test (E) The 7 is green.
1 2 3 4 5 6 7 8 9
Y G E Y
Restriction 2: NOT G-P and Restriction 3: NOT P-G leave only one slot for P: 2P
1 2 3 4 5 6 7 8 9
Y P G E Y
Now we have only single pair of consecutive slots for R-R
1 2 3 4 5 6 7 8 9
Y P G R R E Y
And the remaining slots will be taken by B:
1 2 3 4 5 6 7 8 9
Y P B G R R E B Y
So, using statement  (E) we managed to determine the colors of all the pieces

Answer: (E) The 7 is green.
Answer:

Sunday, February 7, 2010

GRE Math Problem 24

The diagonal of the floor of a rectangular closet is feet. The shorter side of the closet is feet. What is the area of the closet in square feet?
(A)37
(B)27
(C)
(D)
(E)5

Solution for GRE Math Problem 23:

Since and , the product of these two fractions is bigger than 0.333x0.666
Answer:A

Saturday, January 30, 2010

GRE Math Problem 21

The figure below consists of four circles with the same center. The radii of the four circles are 1, 2, 3, and 4.
Compare two values:


Column A
Column B
The area of the shaded region
The area of the yellow region


Solution for GRE Math Problem 20:
Since x + y = a, y + z = b, and x + z = c, a+b+c=2x+2y+2z=2(x+y+z). So, x+y+z=. And the average of x, y and x is
Answer:(D)