Question

if a ,b ,c can do a work in 90,30 and 45 days .if they work together, the time taken to complete the work is

Answer 1

Given that A can do a piece of work in 90 days.

A's 1-day work = 1/90.

Given that B can do a piece of work in 30 days.

B's 1-day work = 1/30.

Given that C can do a piece of work in 45 days.

C's 1-day work = 1/45.


Time is taken to finish the work = 1/90 + 1/30 + 1/45

                                                     = 6/90

                                                     = 1/15.



Therefore the overall time is taken to complete the work = 15days.


Hope this helps

Answer 2

Given that A can do a piece of work in 90 days.
A's 1-day work = 1/90.
Given that B can do a piece of work in 30 days.
B's 1-day work = 1/30.
Given that C can do a piece of work in 45 days.
C's 1-day work = 1/45.

Time is taken to finish the work = 1/90 + 1/30 + 1/45
                                                     = 6/90
                                                     = 1/15.


Therefore the overall time is taken to complete the work = 15days.