Question

6. (15 points) Lucy can mow her yard in 3 hours and 15 minutes. Her brother Will

can mow the same yard in 4 hours and 45 minutes. How long will it take them to

mow the lawn together?

How to solve?

Answer 1

1 hour 56 minutes

Explanation:

Given :

Time taken by Lucy = 3 hours 15 minutes = 3.25 hours

Time taken by brother = 4 hours 45 minutes = 4.75 hours

Rate = 1 / time taken

Lucy's rate = 1 / 3.25

Brother's rate = 1 / 4.75

Combined rate = Lucy's rate + brother's rate

Combined rate = 1/3.25 + 1/4.75

Combined rate = 0.5182186

Time taken if they work together = 1/ combined rate

= 1 / 0.5182186

= 1.9296 hours

= 1 hour (0.9296 * 60) minutes

= 1 hour 56 minutes (approximately)