Work related

rkhicha wrote:Q. If A&B can do a particular task in 15 hours, B&C can do the same task and 12 hours and A&C can complete it in 60/7 hours. How many hours will it take for A, B & C to complete it?

Thanks.

Assume there is 420 units of work

A+B will do 420/15 = 28 units per hour
B+C will do 420/12 = 35 units per hour
C+A will do 420/60/7 = 49 units per hour
Sum of all is 112
112/2 will give A+B+C= 56 units per hour.

Hence they will finish in 420/56 = 60/8=30/4 = 7.5 hours.

Hope this helps!!

rkhicha wrote:Q. If A&B can do a particular task in 15 hours, B&C can do the same task and 12 hours and A&C can complete it in 60/7 hours. How many hours will it take for A, B & C to complete it?

Thanks.

If A&B can do a particular task in 15 hours
A&B can do 1/15 of particular task in 1 hr
B&C can do the same task and 12 hours
B&C can do the 1/12 of same task in 1hours
A&C can complete it in 60/7 hours
A&C can complete7/60 of work in 1 hr

so adding 2(a+b+c) can complete 1/15+1/12+7/60 in 1 hour

2(a+b+c)=16/60 of work in 1 hr
a+b+c will complete 2/15 of work in 1 hr
so a+b+c will complete full wotk in 1/2/15=15/2 hrs

kvcpk wrote:

rkhicha wrote:Q. If A&B can do a particular task in 15 hours, B&C can do the same task and 12 hours and A&C can complete it in 60/7 hours. How many hours will it take for A, B & C to complete it?

Thanks.

Assume there is 420 units of work

A+B will do 420/15 = 28 units per hour
B+C will do 420/12 = 35 units per hour
C+A will do 420/60/7 = 49 units per hour
Sum of all is 112
112/2 will give A+B+C= 56 units per hour.

Hence they will finish in 420/56 = 60/8=30/4 = 7.5 hours.

Hope this helps!!

Very nice solution

Patrick_GMATFix wrote:
Hope this helps!!

Very nice solution[/quote]

Thanks Patrick!!