There are 5 red pens and 10 black pens in a cup. If a person randomly selects 3 of them, what is the probability that they're all the same color?

A. 0.286

B. 0.18

C. 0.264

D. 0.379

option a)

0.286

Step-by-step explanation:

Given that,

number of red pens in cup = 5

number of black pens in cup = 10

number of pen randomly selected = 3

There are 5 red pens and 10 black pens. So there are 5 + 10 = 15 pens in all.

probability of having all red pens = (5/15 x 4/14 x 3/13)

= 2/91

probability of having all black pens = (10/15 x 9/14 x 8/13)

= 24/91

probability that all pen are of same colour = 24/91 + 2/91

= 2/7

≈ 0.286