Question

a bag contains a certain number of balls some of these balls are marked A.,some are marked B and others are C and when ball is drawn at random box P, P (A) =1/3 and P(B) = 1/4..If there are40 balls in a box which are marked C... then find the number of balls marked A​

Answer 1

Answer:

First find probability of ball C

$p(c) = 1 - (p(a) + p(b)) \\ p(c) = 1 - ( \frac{1}{3} + \frac{1}{4} ) = \frac{5}{12}$

Let total balls x , so

$\frac{5}{12} \times x = 40 \\ x = \frac{40 \times 12}{5} = 96 \: \: balls$

So A balls

$a= \frac{1}{3} \times 96 = 32$