Question

An urn contains m green and n red balls. K balls are drawn and laid aside, their colour being ignored. Then one more ball is drawn. Then the probability that it is green

Answer 1

GIVEN :

An urn contains m green balls and n red balls.

TO FIND :

The probability that it is green ball

SOLUTION :

Given that an urn contains m green balls and n red balls.

Total number of balls is m+n

Also given that K balls are drawn and laid aside, their colour being ignored. Then one more ball is drawn.

A green ball is equally distributed anywhere in the sequence.

∵ m of the m+n balls are green balls, the (k+1)st ball selected has probability  $\frac{m}{m+n}$ of being green ball.

∴ The probability that it is green  is $\frac{m}{m+n}$