If 7 subjects are selected from the 9 that are available, and the 7 selected subjects are all treated at the same time, how many different treatment groups are possible?

Question

asked Jan 10, 2021 181k views

1 Answer

Xirehat · Answer 1 · 2021-01-14T22:04:01+0000

Answer:

Therefore, we have 36 different treatment groups.

Explanation:

We know that the 7 subjects are selected from the 9 that are available, and the 7 selected subjects are all treated at the same time.

We calculate how many different treatment groups are possible.

We get:

$C_7^9=(9!)/(7!(9-7)!)=(9\cdot 8\cdot 7!)/(7!\cdot 2\cdot 1)= 36$

Therefore, we have 36 different treatment groups.