Question

$10$ boys and $5$ girls study in a class. Three students are selected at random, one after the other. Find probability that,
(1) First two are boys and the third is a girl,
(2) First and third are boys and second is a girl

Answer 1

$\left(i\right)$ first $2$ are boys and third is a girl

$p\left(bbg\right)=\frac{10}{15}\times \frac{9}{14}\times \frac{5}{13}$

$p\left(bbg\right)=\frac{15}{91}$ Answer

$\left(ii\right)$ first and third are boys and second is given

$p\left(bgb\right)=\frac{10}{15}\times \frac{5}{14}\times \frac{9}{13}$

$p\left(bgb\right)=\frac{15}{91}$ Answer