Question

One pipe can fill up a tank in 'p' hrs and another pipe can fill up the same tank in 'q' hrs. If both the pipes are opened simultaneously to fill the empty tank, they do it in 4 hrs." Which of the following equation suits this condition? 

 P + q = 4

 (1/p + 1/q) = 4

 4p +4q = 1

 4/p + 4/q = 1

MCQ​

Answer 1

Answer:

(1/p + 1/q) = 4

Step-by-step explanation:

(1/p + 1/q) = 4

Answer 2

Answer:

Let's assume for simplicity that the tank has a capacity of 12 units (lcm of 6 & 12, unit can be litres or gallons or anything- just call this unit).

Then the 1st pipe pours in 2 units/hr and 2nd pipe pours in 1 unit/hr (simple maths -> 12units/6hrs is 2units/hr).

If both pipes are opened at same time, units filled per hour is 2+1 = 3 units/hr.

Thus time taken to fill 12 unit capacity of tank is 12 units/(3 units/hr) = 4 hours!

That’s your answer -> 4 hours.

Alternately, you can just use the formula 6*12/(6+12) = 72/18 = 4hrs.

Step-by-step explanation:

hope it will help

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