6. A student is to answer 11 out of 14 questions. Find the number of choices where the student must answer: (a) the first two questions; (b) exactly 3 out of the first 5 questions (c) the first or second question but not both; . (d) at least 3 of the first 5 questions.

A theater has 23 rows of seats. The first row has 20 seats, the second row has 22 seats, the third row has 24 seats, and so on. How many seats are in the theater? The theater has seats.

You and 3 friends are moving into a 4-bedroom house and need to decide who gets which room. How many different ways could you and your friends assign the rooms? (Enter your answer as a whole number.)

Ali, Ben and Calvin divided some stickers among themselves. Ali took 20 stickers and 1/5 of the remaining stickers. Next, Ben took 1/6 of the remaining stickers and 30 more. Finally Calvin took the 240 stickers that were left over. (a) How many stickers did Ben take? (b) How many stickers were there in total at first?