A group of 10 representatives is to be selected out of 12 seniors and 10 juniors. In how many different ways can the group be selected if it should have at least one senior?  Choices.
A) Â²Â²Câ‚â‚€ B) Â²Â²Câ‚â‚€+1 C) Â²Â²Câ‚‰ + Â¹â°Câ‚ D) Â²Â²Câ‚â‚€ - 1 E) None of these
Explanation:   The total number of ways of forming the group of ten representatives is Â²Â²Câ‚â‚€.   The total number of ways of forming the group that consists of no seniors is Â¹â°Câ‚â‚€ = 1 way   The required number of ways = Â²Â²Câ‚â‚€ - 1   ANSWER IS Â²Â²Câ‚â‚€ - 1
<result>D</result>
A group of 10 representatives is to be selected out of 12 seniors and 10 juniors. In how many different ways can the group be selected if it should have at least one senior?