Question

Max can mow a lawn in 45 minutes. Jan takes twice as long to mow the same lawn. If they work together, how long will it take them to mow the lawn?

a.15.0 minutes
b.22.5 minutes
c.30.0 minutes
d.120.0 minutes

Answer 1

A

Explanation:

30 min

Answer 2

c. 30.0 minutes

Explanation:

Max mows 1/45 lawns per minute.

Jan takes twice as long (90 minutes per lawn), so mows 1/90 lawns per minute.

Working together, they mow ...

(1/45 + 1/90) lawns per minute = (2/90 +1/90) lawn/min = 3/90 lawn/min

= 1/30 lawn/min

Then for one lawn, it takes ...

(1 lawn)/(1/30 lawn/min) = 30 min