Question #f19cb

2 Answers
Dec 12, 2017

The time it would take for Jack and Marilyn to mow the lawn​ together will be 2hours and 55 minutes.

Explanation:

Jack mows the lawn in 5 hours.

That means Jack mows 1/5 th of the lawn in 1 hour.

Similarly,

Marilyn can mow the same lawn in 7 hours.

That means, Marilyn mows 1/7 th of the lawn in 1 hour.

So if they work together,

In 1 hour they will mow 1/5 +1/7 th of the lawn, i.e.:

=1/5(7/7) + 1/7(5/5)

= 7/35+5/35 = 12/35th of the lawn is mowed in 1 hour.

That means, they will need 35/12 hours to mow the lawn together,i.e.:

35/12 = 2 11/12 hours.

11/12th of an hour = 11/12 x 60 minutes= 55 minutes.

The time it would take for Jack and Marilyn to mow the lawn​ together will be 2hours and 55 minutes.

Dec 12, 2017

2hrs 55 minutes

Explanation:

In 5 hrs Jack mows 1 Lawn
So in 1 hr Jack mows 1/5 Lawn

In 7 hrs Marilyn mows 1 Lawn
So in 1 hr Marilyn mows 1/7 Lawn

So we can write together Jack and Marilyn in 1 hr can mow 1/5+1/7=(7+5)/35=12/35 Lawn

So they can mow a Lawn i.e. 1 Lawn in 35/12 hrs=2 11/12hrs=2hrs 55 minutes