A and B working separately can do a piece of work in 21 and 24 days, respectively. If they work for a day alternately with A beginning the work, it would be completed in _________.
Answer & explanation
Correct answer: option 3
A = 21 days, B = 24 days,
⇒ They work on alternate days, starting with A,
1st day = 8 units,
2nd day = 7 units,
Every 2 days, 15 units of work is completed,
So in 22 days, 165 units of work is completed,
Therefore, in \( { 22}_{ 8}^{3 } \) days, total 168 units of work is completed.