Question

Driving a tractor, Larry can plow a 1-acre field in 9 h and Sarah can plow a 1-acre field in18 h. If they work together, how long, to the nearest hour, will they take to plow a 1-acrefield

Answer 1

6 hours

Explanation:

Given that:

Time taken by Larry = 9 hours

Time taken by Sarah = 18 hours

Rate:

Larry, a = 1/9

Sarah, s = 1/18

Time taken working together = x

Rate working together = 1 /x

Therefore,

Larry's rate + Sarah's rate = working together rate

1/9 + 1/18 = 1/x

(2 + 1) / 18 = 1/x

3 /18 = 1/x

Cross multiply

3x = 18

3x/3 = 18/3

x = 6

Hence, if they work together, it will take 6 hours