A is twice as efficient as B and takes 45 days less than B to complete a job. Find the number of days in which they can finish the job together.
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 30
The time required to complete the work is the reciprocal of the fraction of work done in one time period.
Efficiency of A = 2(Efficiency of B)
Efficiency -
A : B = 2 : 1
Time taken by A = Time taken by B - 45
Time taken -
A : B = 1 : 2
Difference in time = 2 - 1 = 1
1 ratio = 45 days
A's time = 45 days
B's time = 90 days
(A + B)'s one day work = 1/45 + 1/90 = 3/90 = 1/30
Time taken to complete the work = 30 days