Arithmetic

Time & Work

Medium

applied

Three pipes A, B & C fill a tank in 3 hours working simultaneously. The pipe C is twice as faster as B and B is twice as fast as A. The time taken by pipe A alone to fill the tank is:

27 hours

81 hours

12 hours

21 hours

✅ Correct Option: 4

Three pipes A, B, and C fill a tank in 3 hours working simultaneously. Pipe C is twice as fast as B, and B is twice as fast as A.

Let pipe A take $x$ hours to fill the tank alone.

Since B is twice as fast as A, pipe B takes $\frac{x}{2}$ hours alone.

Since C is twice as fast as B, pipe C takes $\frac{x}{4}$ hours alone.

If a pipe fills a tank in $n$ hours, it fills $\frac{1}{n}$ of the tank in 1 hour.

In 1 hour:

Pipe A fills $\frac{1}{x}$ of the tank

Pipe B fills $\frac{1}{x/2} = \frac{2}{x}$ of the tank

Pipe C fills $\frac{1}{x/4} = \frac{4}{x}$ of the tank

All three pipes together in 1 hour:

$\frac{1}{x} + \frac{2}{x} + \frac{4}{x}$

$= \frac{7}{x}$ of the tank

All three pipes fill the tank in 3 hours, so the work done in 1 hour multiplied by 3 equals 1 complete tank:

$\frac{7}{x} \times 3 = 1$

$\frac{21}{x} = 1$

$x = 21$

Therefore, pipe A alone takes 21 hours to fill the tank.

2026: 25 May Shift 1

Two pipes A and B can fill a tank in 10 minutes & 16 minutes respectively whereas a waste pipe can empty 3 litres per minute. All the three pipes working together can fill the tank in 8 minutes, then the capacity of the tank is:

2025: 29 May Shift 2

Pipe A and B can fill a tank in 15 hours and 20 hours respectively. Pipe C can empty the tank in 25 hours. Pipes A, B and C works together but pipe C is closed after 10 hours , then time taken by pipe A and B to fill the remaining tank is:

2026: 19 May Shift 2

Three pipes A, B and C can fill a tank together in 8 hours. After working at it together for 2 hours, B is closed and A and C can fill the remaining part in 9 hours. The time in which B alone can fill the tank is :

2026: 29 May Shift 1

Two pipes can fill a tank in 20 minutes and 24 minutes respectively, and a waste pipe can empty 3 gallons of water per minute. If all the three pipes working together can fill the tank in 15 minutes, then the capacity of the tank is :

2025: 3 June Shift 2

Pipe A and B can fill a tank in 20 hours and 25 hours respectively, and pipe C can empty the full tank in 40 hours.If all the pipes are opened together, then how much time will be needed to make the tank full?

2025: 27 May Shift 1

Two pipes can fill a tank in 6 minutes and 12 minutes respectively, and a third pipe can empty the tank at the rate of 18 liters per minute. If all the pipes working together can fill the empty tank in 5 minutes, the capacity of the tank is:

Three pipes A, B & C fill a tank in 3 hours working simultaneously. The pipe C is twice as faster as B and B is twice as fast as A. The time taken by pipe A alone to fill the tank is:

Solution

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