The tank will get filled by four A, B, C and D inlets. By A, B and D, tank will get filled in 5 minutes. By A and C inlets, tank will get filled in 20/3 minutes. Through B, C and D inlets, tank will filled in 20/3 minutes. In how much time 3/4th of tank will get filled when all four inlets are opened?
The tank will get filled by four A, B, C and D inlets. By A, B and D, tank will get filled in 5 minutes. By A and C inlets, tank will get filled in 20/3 minutes. Through B, C and D inlets, tank will filled in 20/3 minutes. In how much time 3/4th of tank will get filled when all four inlets are opened? Correct Answer 3 minutes
Calculation:
⇒ 1/A + 1/B + 1/D = 1/5
⇒ 1/A + 1/C = 3/20
⇒ 1/B + 1/C + 1/D = 3/20
Adding all equations,
⇒ 2/A + 2/B + 2/C + 2/D = 1/5 + 3/20 + 3/20 = 1/2
⇒ 2(1/A + 1/B + 1/C + 1/D) = 1/2
⇒ (1/A + 1/B + 1/C + 1/D) = 1/4
Tank will filled in 4 minutes by 4 inlets.
∴ 3/4th tank will be filled in = 3/4 × 4 = 3 minutes.
Important Points
Fraction of tank to be filled × 1/(pipe's 1 hour's work) = Total time in which fraction of work filled