If 18 binders bind 900 books in 10 days, how many binders will be required to bind 660 books in 12 days ?
A)11
B)13
C)22
D)14

Options

A. 14
B. 13
C. 22
D. 11

Answer

To solve the problem step by step, we can use the concept of work done by binders in a given time.

### Step 1: Calculate the work done by the binders in terms of books per day.
We know that:
- 18 binders can bind 900 books in 10 days.

To find out how many books one binder can bind in one day, we first calculate the total work done in terms of books per day.

Total work done (in books) = 900 books
Total days = 10 days

Books bound per day = Total work done / Total days
Books bound per day = 900 books / 10 days = 90 books per day

Now, since 18 binders are binding 90 books per day, we can find out how many books one binder can bind in a day.

Books bound by one binder per day = 90 books / 18 binders = 5 books per binder per day.

### Step 2: Calculate the total work required for the new scenario.
Now, we need to find out how many binders are required to bind 660 books in 12 days.

Total work required = 660 books
Total days = 12 days

Books that need to be bound per day = Total work required / Total days
Books that need to be bound per day = 660 books / 12 days = 55 books per day.

### Step 3: Calculate the number of binders required.
Now, we know that one binder can bind 5 books per day.

To find the number of binders required to bind 55 books per day, we can use the formula:

Number of binders required = Books that need to be bound per day / Books bound by one binder per day
Number of binders required = 55 books per day / 5 books per binder per day = 11 binders.

### Conclusion:
Thus, the number of binders required to bind 660 books in 12 days is **11 binders**.