Question

A alone can complete a job in 12 days and B alone in 18 days. A and B agree to do the work for 7,200. With C's help they finish it in 5 days. How much should C be paid?

• A. ₹2200
• B. ₹2400
• C. ₹2600
• D. ₹2800

Answer 1

Answer:

A. ₹2200

A's 1-day work:

$\frac{1}{12}$

B's 1-day work:

$\frac{1}{18}$
So, A and B together do in 1 day:

$\frac{1}{12}+\frac{1}{18}$
$=\frac{3+2}{36}$
$=\frac{5}{36}$

In 5 days, A and B complete:

$5 \times \frac{5}{36}$
$=\frac{25}{36}$

Therefore, C's contribution in 5 days is:

$1-\frac{25}{36}$
$=\frac{11}{36}$

Since payment is proportional to work done, C's share is:

$7200 \times \frac{11}{36}$
$=200 \times 11$
$=2200$

C should be paid ₹2,200.