Question

Peter can mow his lawn in 6 minutes. Peter's son can mow it in 8 minutes. How long will it take them to do it together?

Answer 1

6 - 6,12,18,24,30,36,42,48,54,60
8 - 8,16,24,32,40,48,56,64,72,80
Answer should be 24 minutes.

Answer 2

3 minutes 26 seconds

Explanation:

rate x time in Distance problems, and W = rate x time in work problems. The Work is generally 1, the whole job.

For Peter the formula is 1 (lawn mowed) = 1/6 lawn per minute x 6 minutes.

For the son the formula is 1 = 1/8 * 8.

Add their rates together, 1/8 + 1/6 = 3/24 + 4/24 = 7/24.

The equation for their rate working together is 1 = 7/24 * t

Divide both sides by 7/24 to find t. t = 1 / 7/24 = 1 * 24/7 = 24/7 = 3 and 3/7 minutes = approx. 3 minutes 26 seconds.