Question 107310
A student is to answer 10 out of 15 exam questions.

a) how many choices has he if he must answer the first 2 questions?

There are 13 choices of which he must answer 8 more to satisfy the 10 answer requierment.

b) how many choices has he if he must answer the first or second question but not both of them?

There are 14 choices of which he must answer 9 more to satisfy the 10 answer requierment.

c) how many choices has he if he mush answer exactly three of the first five questions?

There are 12 choices of which he must answer 7 more to satisfy the 10 answer requierment.

d) how many choices has he if he must answer at least three of the first five questions?

There are 12 choices of which he must answer 7 more to satisfy the 10 answer requierment.

e) how many choices of question has he without restrictions?

10 out of 15

Thanks a lot!

You're welcome.