Question

A bag contains 4white 5red and 6black coloured balls.if the balls are drawn at a random find the probability that no black Ball is drawn?? ​

Answer 1

Step-by-step explanation:

Total number of balls =15

Total number of ways of selecting 3 balls out of 15 balls is

15 CC3 .

Number of black balls =6

Number of non-black balls =9 (4 white, 5 red)

Probability of no ball drawn is black =

15

C

3

9

C

3

=

65

12

Probability of exactly 2 black =

15

C

3

6

C

2

×

9

C

1

=

91

27

Probability of all of same colour i.e. RRR or WWW or BBB

=

15

C

3

4

C

3

+

5

C

3

+

6

C

3

=

(3!)

(15.14.13)

4+10+20

=

455

34.