A and B can do a work in 21 days. A is 7/4 times as efficient as B. In how…
2020
A and B can do a work in 21 days. A is 7/4 times as efficient as B. In how many days, A alone can complete the 200/3 % of the work?
- A.
22
- B.
33
- C.
36
- D.
27
Attempted by 47 students.
Show answer & explanation
Correct answer: A
Given:
A and B together complete the work in 21 days.
Efficiency ratio:
A : B = 7 : 4
Let efficiencies be:
7x and 4x
Combined efficiency:
= 11x
Since total work is completed in 21 days:
11x = 1/21
x = 1/231
Efficiency of A:
= 7x
= 7/231
= 1/33
So, A alone completes 1 unit of work in 33 days.
Now,
Required work = 200/3 %
= 200/3 × 1/100
= 2/3 of the work
Time taken by A to complete 2/3 work:
= 33 × 2/3
= 22 days