Question

If it takes 5 men 20 hours to brick a house, How long will it take 8 men to do the job if they work at the same rate ?

Answer 1

C

Explanation:

Answer 2

-- 5 men take 20 hours to do 1 job .

-- 5 men do 1/20 of a job per hour .

-- 1 man does 1/(5 x 20) = 1/100 = 1% of a job per hour.

-- 8 men do 8/100 of a job per hour .

-- 8 men work at the unit rate of 8/100 job/hr, or 100/8 hr/job.

-- 100/8 hr/job = 12.5 hour per job.

8 men take 12.5 hours .