1 Answers
Option 2 : 3
Given:
Total number of taps = 4
Time taken by each inlet tap to fill the tank = 24 hours
Time taken by each outlet tap to empty the tank = 8 hours
Total time taken to empty the tank = 3 hours
Concept used:
Total work = Time taken × Efficiency
And, Total efficiency = efficiency of intlet taps – efficiency of outlet taps
Calculation:
Let total number of inlet taps be x
Total number of outlet taps be (4 – x)
L.C.M of 24 and 8 = 24 units = Total work
Total time taken to empty the tank = 3 hours
Efficiency of all 4 taps = 24/3 = -8 units
Here, negative sign in efficiency shows tank is emptying
Efficiency of each inlet tap = 24/24 = 1 units
Now, Efficiency of x inlet taps = x
Efficiency of each outlet tap = 24/8 = 3 units
Efficiency of (4 - x) outlet taps = (12 - 3x)
So, Total efficiency of 4 taps = efficiency of inlet taps – efficiency of outlet taps
⇒ Total efficiency of 4 taps = x – (12 – 3x)
So, x – (12 – 3x) = -8
⇒ 4x – 12 = -8
⇒ 4x = 4
⇒ x = 1
⇒ Outlet taps = (4 – 1) = 3
∴ The number of outlet taps is 3