Question

Statistics

Answer 1

Answer:

120

Step-by-step explanation:

The number of ways to select $r$ things from a group of $n$ things is given by the combination formula.

$nCr=\frac{n!}{r!(n-r)!}$

Where n! means n*(n-1)*(n-2)....

• There are 10 total books, so n = 10
• you have to choose 3 books, so r = 3

Plugging these into the formula gives us:

$10C3=\frac{10!}{3!(10-3)!}=\frac{10*9*8*7*6*5*4*3*2*1}{(3*2*1)(7*6*5*4*3*2*1)}=\frac{10*9*8}{3*2*1}=120$

Hence, there can be 120 different groups of 3 books that u can choose from 10 books total.