Question

A bag contains 5 white balls, 6 red balls and 9 green balls. A ball is drawn at random from the bag. Find the probability that the ball drawn is

1. a green ball.
2. a white or a red ball.
3. neither a green ball nor a white ball.

Answer 1

Total number of balls = 5 + 6 + 9 = 20

i. Number of green balls 9, Number of favourable cases

∴ P(Green ball) = `"Number of favourable cases"/"Total number of balls" = 9/20`

ii. Number of white balls 5, Number of red balls 6

Number of favourable cases = 5 + 6 = 11

∴ P(White ball or Red ball) = `"Number of favourable cases"/"Total number of balls" = 11/20`

iii. P(Neither green ball nor white ball) P(Red ball)

= `"Number of Red balls"/"Total number of balls"`

= `6/20`

= `3/10`