Question

A bag contains 8 red and 5 white balls, Three balls are drawn at drawn at random. Find the Probability that

A)All the three balls are white

Answer 1

Applying combination & writing the expression according to the language of equation,

Given,Number of red balls=8

No,of white balls=5

P(all the balls drawn are white)

$=\frac{{}^3{C}_3}{{}^{13}{C}_3}=\frac{5\times 4}{2\times 1}\times \frac{3\times 2\times 1}{13\times 12\times 11}$


$({\therefore }^3{C}_r=\frac{n!}{(n-r)r!})$


$=\frac{5}{143}$