Question

What did I do wrong? (Probability)


A bag of marbles has 12 red, 7 yellow, 5 blue and 1 white. Find the probability of selecting 4 marbles from the bag where all 4 are red.

A. 1/64
B. 9/230
C. 1/4
D. 1/7590
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I got 1/12650 which isn't even an option. I did this my multiplying 1/25*2/25*3*25*4/25.
Which is not an option.

And then 12/390625 by multiplying 4/25*3/24*2/22*1/21 which is also not an option.

Answer 1

there are 12 red marbles, so if we assume there is no replacement it would be

(12/25)*(11/25)*(10/25)*(9/25)

if we assume replacement, it would simply be (12/25)^4

Answer 2

Oh wow.. I put the 4 in place of 12 as the starting point.. Thanks @Vocaloid

Answer 3

ahh, small correction to my formula

(12/25)*(11/24)*(10/23)*(9/22)

Answer 4

but yea, you're on the right track now :)

Answer 5

Thanks :)

Answer 6

It's B. Thanks!