OE

This problem can be solved using an RTW chart or by a proportion. There are 20 minutes between 11:40am and noon, and 40 minutes between noon and 12:40pm. Hector’s work rate is different for the two time periods. For the work period before noon, this is the proportion: Let b represent the number of problems Hector solves before noon:

b/20 minutes=1 problem / 4 min

b=5

Let a represent the number of problems Hector solves after noon:

a/40 minutes=1 problem/10 minutes

a=4


A >B