If Doug can mow the lawn in 3 hours, and Julie can mow the same lawn in 6 hours, how long will it take for both of them to mow the lawn together?
Choose the correct choice from the following answers:
A) 1 hr
B) 2 hr
C) 3 hr
D) 4 hr
E) 5 hr
If Doug can mow the lawn in 3 hours, then in 1 hour he can mow 1/3 of the lawn.   If Julie can mow the lawn in 6 hours, then in 1 hour she can mow 1/6 of the lawn.   Let x = number of hours it would take them together to mow the lawn so,   1/3 + 1/6 = 1/x   x=2 hours   Answer: 2 hr
<result>B</result>
If Doug can mow the lawn in 3 hours, and Julie can mow the same lawn in 6 hours, how long will it take for both of them to mow the lawn together?