In a class of 10 students roll numbers are written on their respective chairs. Find the ways in which exactly 3 students do not sit on their chairs .

Explanation

To solve the problem of finding the number of ways in which exactly 3 students do not sit on their respective chairs in a class of 10 students, we can follow these steps:

### Step 1: Choose 3 Students
First, we need to select 3 students out of the 10 who will not sit in their assigned chairs. The number of ways to choose 3 students from 10 can be calculated using the combination formula:

\[ \text{Number of ways to choose 3 students} = \binom{10}{3} = \frac{10!}{3!(10-3)!} = \frac{10!}{3!7!} \]
...