A can fill the tank in 28hrs
B can fill the tank in 14 hrs
and C takes 7hrs.
If all three pipes are opened simultaneously ,how long it will take to fill the tank?	Choose the correct choice from the following options:
A) 4
B) 5
C) 6
D) 7
E) 8
Solution:time taken=(28*14*7*)/(28*14 + 14*7 + 28*7)   To solve this quicker find out LCM(28,14,7)   we get 28   Time taken =28/(28/28 + 28/14 + 28/7)   =28/(1+2+4)   =28/7= 
<gadget id="calculator">28/7</gadget>
<output>4</output>
4   4nswer 4
<result>A</result>
A can fill the tank in 28hrs
B can fill the tank in 14 hrs
and C takes 7hrs.
If all three pipes are opened simultaneously ,how long it will take to fill the tank?