Question

Mr. rodriguez, a college instructor, can grade his class papers in 3 hours while it takes his assistant 4.5 hours. if mr. rodriguez graded the papers for 1 hour and then left the job for his assistant to complete, how long will it take his assistant to finish grading papers?

Answer 1

The rate of mr Rodriguez to complete 1 job is 1/3 while that of his assistant is 1/4.5.

So if mr Rodriguez works for 1 hour, the job left would be 2/3 of the job. So the total time needed by assistant is:

(2/3) / (1/4.5) = 3 hours

 

Answer:

3 hours