Pipe A can fill a tank in 15 hours, pipe B can fill the same tank in 27 hours and pipe C can fill the same tank in 10 hours. The time taken by them to fill the same tank if they operate together is::

Correct option is C

Given:

Pipe A fills tank in 15 hours

Pipe B fills tank in 27 hours

Pipe C fills tank in 10 hours

Find time when all three work together.

Solution:

A + B + C rates = $$\frac{1}{15} + \frac{1}{27} + \frac{1}{10}$$​​

= $$\frac{18 + 10 + 27}{270}$$​​

= $$\frac{55}{270}$$​​

Time = $$\frac{1}{55/270} = \frac{270}{55} = 4\frac{10}{11}$$​ hours

Alternate Solution (Exam Trick):