Discussion Forum

From a certain population, the probability of choosing a colour blind man is $\frac{1}{20}$ and that of a colour blind woman is  $\frac{1}{10}$ . If a randomly chosen person is found to be colour blind, then the probability that a person is a man is 

Answer:

Explanation:

$P_{CBM}= \frac{1}{20}, P_{CBW}= \frac{1}{10}$

 Person is man= $\frac{1}{2}$ person is woman =$\frac{1}{2}$

$\frac{P_{CBM}}{M}=\frac{\frac{1}{2}.\frac{1}{20}}{\frac{1}{2}.\frac{1}{20}+\frac{1}{2}.\frac{1}{10}}\Rightarrow\frac{.\frac{1}{20}}{\frac{1}{20}+\frac{1}{10}}=\frac{\frac{1}{20}}{\frac{1+2}{20}}\Rightarrow\frac{1}{3}$