A can do a piece of work in 8 days, while B can do it in 7 days. If they work at it alternately beginning with A, then in how many days will the work be completed?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. .
Concept used:
Total work done = Efficiency × time
Calculations:
Total work done by A and B (LCM of 8 and 7) = 56 units
Efficiency of A = 56/8 = 7
Efficiency of B = 56/7 = 8
Total work done by A and B if they work alternatively;
⇒ 7 + 8 = 2 days
⇒ 15 units = 2 days
⇒ 45 units = 6 days
⇒ 52 units = 7 days
Now, B will work but will do half of the work.
⇒ 56 units = 7(1/2) days