Question

A bag contains 10 white and 5 black balls.A ball is randomly picked up from the bag.Find the probablity of getting a black ball

Answer 1

total balls=10+5
=15
Fav. outcomes=5
Probability= fav/total
=5/15
=1/3

Answer 2

given :
a bag contains 10 white balls, 5 black balls

need to find out :
probability of black ball

solution :
total number of balls 10+5 = 15 balls
probability = favor of black balls coming out / total number of balls 
                   =  5 / 15 
                  = 1/3
therefore the probability of black balls = 1/3