Question

Question #0c12f

Answer 1

`"_13C_4 = 715`

Explanation:

this seems like a combination problem where we select `"_13C_4 = 715`. this means that out of the 13 times there are 715 where times where we can group 4 items differently in this case representing the heads.

Answer 2

`""_13C_4=(13!)/(4!*9!)=715`

Explanation:

You have a sequence of `13` outcomes;
Exactly `4` of these outcomes must be Heads;
that is, we need to choose `4` locations within `13` where Heads are to occur.

`""_13C_4=(13!)/(4! * 9!)=(13xx12xx11xx10)/(4xx3xx2xx1)=715`

Note: we could have just as well thought of this as choosing `9` locations in the sequence for the Tails since `""_13C_4=""_13C_9`