Question

An um contains 8 red, 3 white and 9 blue balls. If three balls are drawn at random, determine the probability that


1)all three are red

2)all three are blue

3)none of the balls drawn is white

​

Answer 1

Step-by-step explanation:

8 red, 3 white, 9 blue

total = 20

total no. of ways of drawing 3 balls = 20C3

1) 'e', be no. of ways of drawing 3 red balls = 8C3

p(e) = 8C3 / 20C3

= 8×7×6 / 20×19×18 = 0.05

2) 'a', be no. of ways of drawing 3 blue balls = 9C3

p(b) = 9C3 / 20 C 3

= 9×8×7/20×19×18 =0.074

3) b = none are white

= no. of ways of drawing 3 balls from mix of red and blue(8+9=17)

= 17c3

p(b) = 17c3 / 20c3

= 17×16×15/ 20×19×18 =0.6