Find the number of different ways a grade of A B C or D can

Find the number of different ways a grade of A, B, C, or D can be assigned to three students of a class so that no two students receive the same grade.

Solution

Let us represent three students by S1, S2 and S3 who can get A,B,C or D grade

Given that no 2 students should get same grade

let S1 can be given 1 grade out 4

therefore total number of ways to grade S1 =4

as no 2 students can be given same grades therefore

total number of ways to grade S2 =3

Similarily,

total number of ways to grade S3=2

hence the number of different ways a grade of A, B, C, or D can be assigned to three students of a class so that no two students receive the same grade is = 4*3*2 = 24