Question

In how many ways can 3person study groups beselected from a class of 25students?Note: nrn!r!(n-r)!nEnter

Answer 1

Answer:

2,300

Explanation:

This is given as:

$\begin{gathered} 25\text{ combination 3 represented as:} \\ ^nC_r=\frac{n!}{r!(n-r)!} \\ n=25 \\ r=3 \\ ^{25}C_3=\frac{25!}{3!(25-3)!} \\ ^{25}C_3=\frac{25\times24\times23\times22!}{3!\times22!} \\ ^{25}C_3=\frac{25\times24\times23}{3\times2\times1} \\ ^{25}C_3=2300 \end{gathered}$

Therefore, there are 2,300 ways that 3 persons can be selected from 25 people