Question : Pipe A can fill a tank of capacity 350 litres in $3 \frac{1}{2}$ minutes. Pipe B can fill a tank of capacity 780 litres in $8 \frac{2}{3}$ minutes. How long (in min) will it take to fill a tank of capacity 1615 litres, if both pipes are opened together?
Option 1: $9$
Option 2: $7 \frac{1}{2}$
Option 3: $8 \frac{1}{2}$
Option 4: $8$
Correct Answer: $8 \frac{1}{2}$
Solution :
Use: Time taken by a pipe = $\frac{\text{Capacity of tank}}{\text{Efficiency of a pipe}}$
Given:
Pipe A can fill a tank of capacity 350 litres in $3\tfrac{1}{2}$ minutes
Pipe B can fill a tank of capacity 780 litres in $8\tfrac{2}{3}$ minutes
Now,
Pipe A can fill a tank in $1$ minute = $350 × \frac{2}{7}\ = 100$ litres
Pipe B can fill a tank in $1$ minute = $780 × \frac{3}{26}\ = 90$ litres
Pipe A and Pipe B together fill the tank in 1 min = $100\ +\ 90\ =\ 190$ litres
So,
1615 litres will be filled by the pipe A and pipe B in $\frac{1615}{190} = 8\tfrac{1}{2}$ minutes
Hence, the correct answer is $8\tfrac{1}{2}$.
Related Questions
Know More about
Staff Selection Commission Sub Inspector ...
Application | Eligibility | Selection Process | Result | Cutoff | Admit Card | Preparation Tips
Get Updates BrochureYour Staff Selection Commission Sub Inspector Exam brochure has been successfully mailed to your registered email id “”.