Question

Janet can do a job in 3 hours while Garry can do the same job in 2 hours. If Janet works for an hour before Garry began helping her, how long will it take them to finish the job together?

Answer 1

Answer: 4/5 of an hour or 48 minutes

Explanation:

Janet's Rate : 1 job / 3 hours = 1/3 job/hour

In 1 hour, 1/3 of the job is already finished by her, so there is 2/3 of the job left.

Garry's Rate:

1 job / 2 hours = 1/2 job/hour

Janet an Garry's Rate:

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

Time to do remaining 2/3 of job:

2/3 job / 5/6 job/hour = 2/3 * 6/5 hour = 4/5 hour

Answer:

It will take 4/5 of an hour for them to finish the job together.

I Hope This Helps!

Answer 2

4/5 hour (48 minutes)

Explanation:

Janet works at the rate of ...

(1 job)/(3 hours) = (1/3) job/hour

So, in 1 hour, she has worked 1/3 of the job, leaving 2/3 of the job remaining when Garry shows up.

Garry works at the rate of ...

(1 job)/(2 hours) = 1/2 job/hour

So, together they work at the rate of ...

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

Then the time it takes to do the remaining 2/3 job is ...

(2/3 job)/(5/6 job/hour) = (2/3·6/5) hour = 4/5 hour

It will take 4/5 hour for them to finish the job together.