Question

Deandra is doing her math homework. Out of 24 problems total, she completed the first 12 problems in 1 hour and the last 12 problems in 3 hours. What is the unit rate for all 24 problems?

Answer 1

To find unit rate for all 24 problems.  
12 problems completed in 1 hour = 12 in 60 minutes
 Last 12 problems in 3 hours = 12 in 180 minutes
 Total 24 in (180+60= 240) minutes
 Time taken to solve one problem = 240/24 = 10 minutes. 
 This means Deandra on an average took 10 minutes to solve each problem.

Answer 2

If you divide 12 by 3 the correct answer should be 4 problems per hour.