Advanced MathEasy–MediumRational equation from a work context
Advanced Math practice question
Working alone, one pump can empty a tank in 2 hours and a second pump can empty it in 3 hours. The time t, in hours, for the two pumps working together satisfies 1/2 + 1/3 = 1/t. What is the value of t?
Answer: 6/5 or 1.2
1/2 + 1/3 = 5/6, so 1/t = 5/6 and t = 6/5 = 1.2 hours.
Common wrong answers
- If you answered 5
- 5 adds the two times; working together is faster than either pump alone.
- If you answered 2.5
- 2.5 averages the times, which is not how combined rates work.
- If you answered 0.83
- 0.83 is 5/6, the combined RATE (tanks per hour), not the time.
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