Question

We wish to select 6 person from 8 but, if the person A is choosen, then B must be choosen. In how many ways can selections be made?

Answer 1

Total number of persons = 8 

Number of persons to be selected = 6

Condition is that if A is choosen, B must be choosen

Case I: When A is choosen, B must be choosen 

Number of ways = ⁶C₄ [∴ A and B are set to be choosen]

Case II: When A is not choosen, then B may be choosen 

∴ Number of ways =⁷C₆

Hence, the required number of ways = 22