Question

A bag contains 9 red 7 white and 4 black balls. One ball is drawn at random. the probability that it is red ( a) 7/20 (b) 9/20 (c) 11/20 (d) 13/20​

Answer 1

Answer:

Total number of ways of selecting 3 balls out of total without replacement = 20C3 .

And the number of ways of selecting three non white balls without replacement = 13C3

Thus the required probability is

=13C3 / 20C3

= 13*12*11/(20*19*18)

= 0.250877

Step-by-step explanation:

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Answer 2

Answer: (c) 11/20

Since, total no. of balls = 9+7+4=20

No. of balls that are not red = 7+4=11

∴ Required probability = 11/20