If pipe A can fill 350 litres in 3\(\frac{1}{2}\) min. Pipe B can fill 780 litres in 8\(\frac{2}{3}\) min. Find the time taken by both of them to fill 1615 litres.
Answer & explanation
Correct answer: option 2
Time Amount (ltr)
A → 3\(\frac{1}{2}\) min → 350
1 min → 100
B → 8\(\frac{2}{3}\) min → 780
1 min → 90
⇒ Efficiency of A → 100 l/min
⇒ Efficiency of B → 90 l/min
⇒ Eff. of A + B = 190 l/min
Time taken by A and B both = \(\frac{Total\;amount\;to\;be\;filled}{combined\;efficiency}\)
= \(\frac{1615}{190}\)
= 8.5 min or 8\(\frac{1}{2}\) min