2
algebra

A pipe fills a tank in 4 hours. Another drains it in 6 hours. If both are open, how long to fill the tank?

A

5

B

2

C

10

D

12

Correct Answer: D

Choice Dhoice D is the correct answer.

  1. Rates: Fill = 1/41/4, Drain = −1/6-1/6.
  2. Equation: 14−16=1t\frac{1}{4} - \frac{1}{6} = \frac{1}{t}
  3. Common Denominator (12): 312−212=112\frac{3}{12} - \frac{2}{12} = \frac{1}{12}
  4. Solve: t=12t = 12

Choice Dhoice B is incorrect because calculation error.

Choice Dhoice C is incorrect because calculation error.

Choice Dhoice A is incorrect because calculation error.

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Linear Functions Set 32