Malorie can work 10 math problems in 3 minutes. At this rate, how many problems can she work in one hour?

a. 30

b. 60

c. 120

d. 200

D

If you multiply 3 by 10 and add a zero onto the ten in the question that is 100 in half an hour, all you need to do then is multiply that answer by two to get your answer.