If 72 binders can bind 720 books in 22 days, how many binders will be required to bind 660 books in 12 days?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 121.
72 binders can bind 720 books = 22 days
Therefore, the total work done = 72 × 22 = 1584 binder-days
Rate of binding per binder per day = 720/1584 = 0.4545 books per binder per day
Total work (binder-days) = x × 12 (binder = x)
The total amount of work is also the number of books bound = 660.
So, the same rate of binding per binder per day = x × 12 × 0.4545 = 660
⇒ x × 5.454 = 660
⇒ x = 660/5.454 = 121.1 or 121
Thus, 121 binders will be required to bind 660 books in 12 days.