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by manasi_sh » Sun Oct 07, 2007 8:47 am
What was John’s average driving speed in miles per hour during a 15-minute interval?
(1) He drove 10 miles during this interval.
(2) His maximum speed was 50 miles per hour and his minimum speed was 35 miles per hour during this interval.
ANS is A
but why not "D"?..

2nd SUM: Is quadrilateral Q a square?
(1) The sides of Q have the same length.
(2) The diagonals of Q have the same length.
ANS: C

3rd Sum: . Is x2 – y2 a positive number?(x2= x square, y2= y square)
(1) x – y is a positive number.
(2) x + y is a positive number
ANS:C

4th Sum: The surface area of a square tabletop was changed so that one of the dimensions was reduced by 1 inch and the other dimension was increased by 2 inches. What was the surface area before these changes were made?
(1) After the changes were made, the surface area was 70 square inches.
(2) There was a 25 percent increase in one of the dimensions.
ANS: D
Source: — Data Sufficiency |

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by arocks » Sat Oct 13, 2007 11:53 am
3rd Sum: . Is x2 – y2 a positive number?(x2= x square, y2= y square)
(1) x – y is a positive number.
(2) x + y is a positive number

x^2 -y^2 = (x+y)(x-y)

stmt1 x-y is positive
but x+y could be positive or negative, so insuff.

stmt2 x+y is positive
but x-y could be positive or negative, so insuff.

Combining 1 and 2: positive*positive = positive

So the ans is C


2nd SUM: Is quadrilateral Q a square?
(1) The sides of Q have the same length.
(2) The diagonals of Q have the same length.

stmt1 - could be a square or a rhombus. So insuff.
stmt2 - could be a square or a rectangle. So insuff.

Combining 1 and 2 - square.

So the ans is C

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by Suyog » Sat Oct 13, 2007 4:36 pm
manasi_sh,

you have already posted these same questions before and i have posted ans for all of them.

pls chk the following link.

https://www.beatthegmat.com/viewtopic.php?t=5950

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