A does 60% of a work in 15 days. He then calls B, and they together finish the remaining work in 5 days. How long B alone would take to do the whole work?
A) 25 days B) 20 days C) 80 days D) 24 days
Answers
Step-by-step explanation:
60% of work is done by A in = 15 days.
100% of work will be done by A in =15 x 100/60=25 days.
In 1- day A can do= 1/25 work.
0.4 part of work is done by A and B in 5- days.
So in 1- day A and B can do= 0.4/5 =2/25 work
So 1/A + 1/B= 2/25 work
Therefore 1/B= 2/25 - 1/A
= 2/25 - 1/25
= 1/25.
So “B” alone can complete the whole work in 25- days. ============================
Simple Method : 60% of work is done by A in 15- days.
The remaining 40% of the work will be done by A in = 15 x 40/60=10days.
In 1-day A can do= 0.4/10= 1/25 work.
The remaining 40% of work is done by A and B in 5- days.
Ie., In just half the time in which “A” can do !!.
So both A and B are equally efficient and B can do as much work as A !!
Therefore “B” alone can do in 1-day 1/25 of work .
So B can finish the complete work alone in 25- days.