Question:medium

The circumference of an inlet pipe and an outlet pipe is 15 cm and 10 cm respectively. How long will it take the tank to be filled, when it is empty and both pipes are opened?

Statement (1): Outlet pipe can empty the tank in 25 minutes.
Statement (2): Inlet pipe can fill the empty tank in 56 minutes.

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Ignore the pipe circumferences; you just need each pipe's individual fill/empty rate, and each statement gives only one of the two.
Updated On: Jul 20, 2026
  • If the data in statement (1) alone is sufficient to answer the question, but the data in statement (2) alone is not sufficient.
  • If the data in statement (2) alone is sufficient to answer the question, but the data in statement (1) alone is not sufficient.
  • If the data in both the statements together are needed to answer the question.
  • If either statement (1) alone or statement (2) alone is sufficient to answer the question.
  • If the data in neither statement (1) nor statement (2) is sufficient to answer the question, and more data is needed.
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The Correct Option is C

Solution and Explanation

Use the LCM method instead of fractions. Take the tank's capacity as the LCM of 56 and 25, which is $1400$ units.
From statement (2), the inlet fills $1400/56 = 25$ units every minute.
From statement (1), the outlet drains $1400/25 = 56$ units every minute.
With both pipes open, the net change per minute is $25 - 56 = -31$ units, meaning the tank actually empties faster than it fills and would never reach full, which is itself a valid, determinate answer to "how long will it take to fill".
Neither statement by itself gives both rates: statement (1) alone tells us only about the outlet, and statement (2) alone tells us only about the inlet, so on its own neither can settle the question.
Only by combining both statements can we work out what actually happens, so the correct choice is (c), both statements together are needed.
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