PLS HELP!! If the mean (average) of a set of 6 numbers is 15, which of the following statements must be true?

A. The median of the set of numbers is 12.

B. The mode of the set of numbers is 15.

C. The range of the set of numbers is 48.

D. The sum of the set of numbers is 90.

On average, how many more hits will he get when he bats 100 times at home during the day as opposed to 100 times away at night?

Quick! a survey of 57 customers was taken at a bookstore regarding the types of books purchased. the survey found that 33 customers purchased mysteries, 25 purchased science fiction, 18 purchased romance novels, 12 purchased mysteries and science fiction, 9 purchased mysteries and romance novels, 6 purchased science fiction and romance novels, and 2 purchased all three types of books. a) how many of the customers surveyed purchased only mysteries? b) how many purchased mysteries and science fiction, but not romance novels? c) how many purchased mysteries or science fiction? d) how many purchased mysteries or science fiction, but not romance novels? e) how many purchased exactly two types of books?

Two cars which are 40 miles apart start moving simultaneously in the same direction with constant speeds. if the speed of the car which is behind is 56 mph and the speed of the other car is 48 mph, how many hours will it take for the car which is behind to catch up the car ahead of it?