It takes Sarah 4 1/3 min to complete five math problems. If an assignment has 9 problems, how many min will it take Sarah to complete the assignment.

Answer 1

You set a problem like this up as a ratio. 4 1/3 over 5 equals p over 9.

4 1/3 / 5 = p / 9

Then you cross multiply -- multiply the top of the first fraction times the bottom of the second, and the bottom of the first time the top of the second.

4 1/3 x 9 = 39

5 x p = 5p

Now you have 5p = 39

Divide both sides by 5: p = 7 4/5

I will take her 7 4/5 minutes.