# If 18 Binders Bind 900 Books in 10 Days, How Many Binders will be Required to Bind 660 Books in 12 Days?

### Computer MCQs Series for PPSC, FPSC – Most Repeated MCQs | Set 6

• If 18 binders bind 900 books in 10 days.
• Binders required to bind 660 books in 12 days can be figure out in this way.

## Explanation

Three given entities here are

1. Books
2. Days
3. Binders

To determine the relation here, let suppose; Binders required to bind 660 books in 12 days = y

Case I

Books        Binders

900             18

660            y

• More books mean more binders.
• Less books mean less binders.

This clearly indicates that there is direct relation.

Direct/Indirect relation tells how the equation will be written.

900 : 660  ::  18 : y ________ (i)

Case II

Days           Binders

10               18

12               y

• More days mean less binders.
• Less days mean more binders.

This clearly indicates that there is inverse relation.

Direct/Indirect relation tells how the equation will be written.

12 : 10  ::  18 : y ________ (ii)

By (i) and (ii)

900 : 660  ::  18 : y

12 : 10

900 x 12 x y = 660 x 10 x 18 ________ (A)

After simplifying equation (A), we can easily figure out the value of y (y = 11)

## To Find

Binders required to bind 660 books in 12 days = ?

## Solution

### Method I

Let suppose

Binders required to bind 660 books in 12 days = y

Books        Days          Binders

900             10               18

660            12               y

• Relation between books and binders is direct.
• Relation between days and binders is inverse.

So

900 : 660  ::  18 : y

12 : 10

900 x 12 x y = 660 x 10 x 18

10800y = 118800

y = 118800/10800

y = 11

Binders required to bind 660 books in 12 days = 11 binders answer

### Method II

Binders required to bind 900 books in 10 days = 18 binders

Binders required to bind 900 books in 1 day = (18 x 10) binders

Binders required to bind 900 books in 1 day = 180 binders

Binders required to bind 1 book in 1 day = 180/900 binders

Binders required to bind 1 book in 1 day = 1/5 binders

Binders required to bind 660 books in 1 day = 660/5 binders

Binders required to bind 660 books in 1 day = 132 binders

Binders required to bind 660 books in 12 days = 132/12 binders

Binders required to bind 660 books in 12 days = 11 binders

Binders required to bind 660 books in 12 days = 11 binders answer

### Conclusion

If 18 binders bind 900 books in 10 days, 11 binders will be required to bind 660 books in 12 days.