Bunuel wrote:

From a class of 12 students, two students will be randomly chosen simultaneously. If g is the number of girls in the class, what is the value of g?

(1) The probability that two girls will be chosen together is 1/11.

(2) The probability that one boy and one girl will be chosen is 16/33.

Let the number of girl be g, then the number of boys =12-g...

(1) The probability that two girls will be chosen together is 1/11.

P of first as girl = g/12..

P of second as girl = (g-1)/11..

Combined prob = g/12 * (g-1)/11=1/11...

g (g-1)=12=4*3...

So g is 4

Sufficient..

2) The probability that one boy and one girl will be chosen is 16/33..

Whatever Ans we get can be of boys or girls..

So insufficient..

(12-g)/12 *g/11 * 2=16/33....... (12-g)g=32...

So g can be 8 or 4..

Insuff

A

Hi, thanks for the answer.