Question

There are 20 students on the varsity baseball team. Nine of the students will be on the starting lineup. The coach calls out the names of the players on the list in no particular order. How many different list of students could be read?

Answer 1

you simply just multiple the number of students 
(20)
and the amount on the starting line up 
(9)
and get...
180 
I hope this helped!

Answer 2

Answer: 167,960

Step-by-step explanation:

Number of combinations of n things taking r at a time is given by :-

$C(n;r)=\dfrac{n!}{r!(n-r)!}$

Given : There are 20 students on the varsity baseball team.

9 of the students will be on the starting lineup.

The coach calls out the names of the players on the list in no particular order (so we use combinations).

Then, the number of different list of students could be read is given by :-

$C(20\ ;9)=\dfrac{20!}{9!(20-9)!}\\\\=\dfrac{20\times19\times18\times17\times16\times15\times14\times13\times12\times11!}{9\times8\times7\times6\times5\times34\times3\times2\times1\times11!}\\\\=167960$

Hence, the number of different list of students could be read= 167,960