Question

A stack of nested paper cups is 8 inches tall . The 1st cup is 4 inches tall and each of the rest of the cups in the stack adds 1/4 of an inch to the height of the stack. How many cups are in the stack?

Answer 1

17

Explanation:

For n cups, the height of the stack is ...

4 + (1/4)(n -1)

For a height of 8 inches, we can find n from ...

8 = 4 +(1/4)(n -1)

4 = (1/4)(n -1) . . . . . . subtract 4

16 = n -1 . . . . . . . . . .multiply by 4

17 = n . . . . . . . . . . . .add 1

There are 17 cups in the stack.