A bag contains 8 red marbles, 7 white marbles, and 8 blue marbles. You draw 5 ma

Question

A bag contains 8 red marbles, 7 white marbles, and 8 blue marbles. You draw 5 marbles out at random, without replacement.

What is the probability that all the marbles are red?

Everything I have found on this type of question online says I'm doing it right

(8/23)(7/22)(6/21)(5/20)(4/19) or (8 nCr 5)/(23 nCr 5) which is .0017 but the website keeps saying I am wrong. Is there something I'm not seeing here?

What is the probability that exactly two of the marbles are red?

What is the probability that none of the marbles are red?

Explanation / Answer

total number of possibilites = 23 C 5

a)

probability that all marbles are red = 8C5 / 23C5 = 0.00166

its the right way may some rounding error

so instead of rounding they just chopped the 6 , so try 0.0016

b)

required probability = 8C2 * 15C3 / 23C5 = 0.3786

c)

required probability = 15C5 / 23C5 = 0.08925

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