Question

Janet can do a job in 3 hours, and Garry can do the same job in 2 hours. If Janet works for 1 hour before Garry comes to help, how long will it take them to do it together.

Answer 1

1 4/5

Explanation:

Answer 2

48 minutes

Explanation:

Given that:

Time taken by Janet = 3 hours

Janet's rate = 1/3 job / hour

Time taken by Garry = 2 hours

Garry's rate = 1/2

Rate of working together :

1/3 + 1/2 = (2 + 3) /6 = 5/6 job/hour

If Janet works for one hour before Garry joins ;

1/3 of the job has been done by Janet

1 - 1/3 = 2/3 of the job left

Hence to finish the job together, it will take :

Fraction of JOB left ÷ rate of working together

(2/3 ÷ 5/6)

= 2 /3 * 6/5

= 12 / 15

= 4 / 5 hours

To minutes

(4/5) * 60

= 240/5

= 48 minutes