(Q2) A bag contains 5 red balls and some blue balls. If the probability of drawing a blue ball is double that of a red ball, determine the number of blue balls in the bag.

Answer :

Number of red balls in the bag = 5 As the probability of blue balls is double the probability of red balls, we have that number of blue balls is double the number of red balls.

∴ Blue Balls =

( !! Let the number of blue balls = x

Number of red balls = 5

Total no. of balls = +

Total outcomes in drawing a ball at random = +

Number of outcomes favourable to red ball = 5

from the problem,

+ = )