Correct Answer - Option 1 : 30 days
Given:
Time taken to complete a piece of work by B = x
Time taken to complete same work by A = x + 50%
Formula used:
Efficiency = Work/Time
Calculation:
Let us consider the number of days B requires to complete the work = x days
So, number of days A requires to complete the work = x + (50/100)x = 1.5x
We can calculate, work done by A in 1 day = 1/1.5x = 2/3x
And work done by B in 1 day = 1/x
We know that the number of days A and B together requires to do work = 18 days
So, work done by both A and B in 1 day = 1/18
⇒ 2/3x + 1/x = 1/18
⇒ 5/3x = 1/18
⇒ x = (5× 18)/3
⇒ x = 30
∴ B requires 30 days to complete the work.