Question

A bag contains 90 balls. The ratio of the colours red to white to blue
is 1:2:3
a) Calculate the probability of choosing:
(i) a red ball
(ii) not a red ball
(iii) a white or a red ball.
b) How many balls of each colour are there?​

Answer 1

Answer:

Let x be the no. of red balls

2x be the no. of white balls

3x be the no. of blue balls.

Total no. of balls =90

=x+2x+3x=90

=6x=90

=x=90/6

=x=15

Thus, no. of red balls =15

no. of white balls=15×2 =30

no. of blue balls =15×3=45

a)

i) Probability of choosing red ball

=15/90

=6

ii)Probability of choosing not a red ball

=(no.of white ball+no. of blue balls)/90

=(30+45)/90

=75/90

=5/6

iii) Probability of choosing a white or a red ball

=(no.of white ball+no.of red ball)/90

=(30+15)/90

=45/90

=1/2

b)no. of red balls =15

no. of white balls=15×2 =30

no. of blue balls =15×3=45