help~

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help~

by likewhoa » Sun Nov 25, 2007 6:38 am
If each of the students in a certain mathematics class is either a junior or a senior, how many students are in the class?

(1) If one student is to be chosen at random from the class to attend a conference, the probability that the student chosen will be a senior is 4/7

(2) There are 5 more seniors in the class than juniors.

answer:C
Source: — Data Sufficiency |

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by sujaysolanki » Sun Nov 25, 2007 8:41 am
Have no clue ... :(

Stem Total = S + J


Stmt 1 P (S) = 4/7

Stmt 2 S= J + 5

Can we use the probablity in stmt 2 ..only then it wud be possible ..but am not sure ...anyone care to explain ... :?

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by ri2007 » Sun Nov 25, 2007 9:25 am
statement 1 ) We get ratio of S: J = 4:3 - Total = 7
Statement 2) J = x, then S = X +5
Combined = x+5/ x = 4/3
So X = 15 and 7x = 105

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by sujaysolanki » Sun Nov 25, 2007 7:19 pm
got it thnks