Question

There are 5 red balls,4 blue balls and n green balls inside a bag.A ball is taken from the bag at random.Given that the probability of picking a green ball is 0.4,find thr value of n.

Answer 1

This means that the probability of picking both red and blue balls would have to be 60% or 0.6

$\frac{9}{x} =0.6 \\ 0.6x=9 \\ x=9(0.6) \\ x=15 \\ \frac{n}{15} =0.4 \\ n=0.4(15) \\ n=6$