sandy wrote:
Working alone Jerry can complete a work in 6 minutes.Working alone ,Adam can complete a work in 8 minutes.Working together,Jerry leaves the work after 2 minutes.How long will it take Adam to complete the work?
Let's assign a NICE VALUE to the job that needs to be completed.
We have completion times of 6 minutes and 8 minutes, so let's say the "job" consists of making 24 widgets (I chose this value, because 6 and 8 both divide nicely into 24)
Jerry can complete a [job] in 6 minutesIf the job is to make 24 widgets, we can see that Jerry can make
4 widgets/minuteAdam can complete a [job] in 8 minutesIf the job is to make 24 widgets, we can see that Adam can make
3 widgets/minuteGiven: they work
together for 2 minutes.
Together, their combined output =
4 widgets/minute +
3 widgets/minute =
7 widgets/minuteSo, in 2 minutes, their TOTAL output = (2 minutes)(
7 widgets/minute) = 14 widgets
If the total job is to make 24 widget, then there are still 10 widgets to make (24 - 14 = 10)
Then Jerry leavesAdam can make
3 widgets/minute.
He must make 10 widgets
Time = output/rate = 10/
3 = 10/3 minutes
Answer: 10/3 minutes or 200 seconds
Cheers,
Brent
_________________
Brent Hanneson - founder of Greenlight Test Prep