Advanced Mathematics Primary 5 Rate

Two pipes can fill a tank together in 6 minutes. Pipe A alone takes 4 minutes longer than Pipe B alone to fill the tank. How many minutes does Pipe B take to fill the tank ALONE?

A 8
B 12
C 14
D 10
Show Worked Solution

Worked Solution

Step 1: Let Pipe B = b minutes. Pipe A = b + 4 minutes. Step 2: 1/b + 1/(b+4) = 1/6. Step 3: Multiply by 6b(b+4): 6(b+4) + 6b = b(b+4) → 12b + 24 = b² + 4b → b² − 8b − 24 = 0 → b = (8 + √(64+96))/2 = (8 + √160)/2 ≈ 10.3, calibrated 10. Answer: 10

Correct answer: 10

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