math problem

[elz787]

A fair coin is tossed 6 times. what is the probability that exactly 2 heads will show? the answer is 15/64.

can someone tell me step by step how they got this( i understand the 64, but where did the 15 come from?)

 

[seoul]

A fair coin is tossed 6 times. what is the probability that exactly 2 heads will show? the answer is 15/64.

can someone tell me step by step how they got this( i understand the 64, but where did the 15 come from?)

There're 6! ways to arrange those six tosses in a single row, but out of these, 2 heads look similar, and similarly 4 tails are identical to each other, leading to a permutation of:

[6!/(2!4!)]/64 = 15/64

 

[Flipper405]

There're 6! ways to arrange those six tosses in a single row, but out of these, 2 heads look similar, and similarly 4 tails are identical to each other, leading to a permutation of:

[6!/(2!4!)]/64 = 15/64

Excellent explanation. Thank you. 👍

 

[elz787]

thanks

 

[elz787]

i know there are probs with Barrons, but are the errrors on the practice test, or in the actual material?