Word problem- data sufficiency problems

[\'manpreet singh]

Q.1)If Car X followed Car Y across a certain bridge that is 1/2 mile long, how many seconds did it take Car X to travel across the bridge?
(1) Car X drove onto the bridge exactly 3 seconds after Car Y drove onto the bridge and drove off
the bridge exactly 2 seconds after Car Y drove off the bridge.
(2) Car Y traveled across the bridge at a constant speed of 30 miles per hour.

Q.2)What percent of the drama club members enrolled at a certain school are female students?
(1) Of the female students enrolled at the school,40 percent are members of the drama club.
(2) Of the male students enrolled at the school,25 percent are members of the drama club.

[Anurag@Gurome]

Q.1)If Car X followed Car Y across a certain bridge that is 1/2 mile long, how many seconds did it take Car X to travel across the bridge?

(1) Car X drove onto the bridge exactly 3 seconds after Car Y drove onto the bridge and drove off the bridge exactly 2 seconds after Car Y drove off the bridge.
(2) Car Y traveled across the bridge at a constant speed of 30 miles per hour.

Statement 1: All we know is that X takes 1 second less to cross the bridge than Y.

Not sufficient

Statement 2: We don't know the speed of X or relation of speed of X with that of Y.

Not sufficient

1 & 2 Together: We know speed of Y. Hence, we can determine how much time it will take to cross the bridge. Therefore, we can determine how much time X will take to cross the bridge.

Sufficient

The correct answer is C.

Note : If anyone is interested in the calculation (which is really not necessary)...
Y will take (1/2)/30 hours = 1/60 hours = 60 seconds to cross the bridge.
Hence, X will take (60 - 3 + 2) = 59 seconds to cross the bridge.

[Anurag@Gurome]

Q.2)What percent of the drama club members enrolled at a certain school are female students?

(1) Of the female students enrolled at the school,40 percent are members of the drama club.
(2) Of the male students enrolled at the school,25 percent are members of the drama club.

Looking at the statements I can guess that none of them are individually sufficient as none of them provides a definite relation between the number of female members and total number of members. Hence, I'm going to analyze the problem taking both statements into consideration.

Say, the school has M male students and F female students.
Hence the drama club has M/4 male members and 2F/5 female members.
Hence, required percentage = (2F/5)/(M/4 + 2F/5)

As we don't know M and F or the relation between M and F, we cannot determine the percentage.

The correct answer is E.

[\'manpreet singh]

Thanks for the quick reply!!