January Student Problem of the Month

Jan 17, 2019 | Anthem

Problem:

Jake can mow a lawn in 3 hours. Kelly can mow a lawn in 4 hours. If they work together, how long will it take them to mow a lawn?

Solution:

Jake mows 1/3 of a lawn each hour.  Kelly mows 1/4 of a lawn each hour.  To find out how much BOTH students mow in one hour, we add: 1/3 + 1/4 = 7/12 of a lawn each hour.

Mowing for t hours at 7/12 lawns per hour to complete 1 lawn, we have the equation:

(7/12)t = 1

Solving for t, we get:

t = 12/7 hours