Tap A fills a tank in 25 minutes, Tap B fills it in 40 minutes, and Tap C empties it in 30 minutes. If all three taps are opened together on an empty tank, will the tank be filled or emptied, and in how many minutes?

Introduction / Context:
Sum the two inlet rates and subtract the outlet rate. If the net is positive, the tank fills; if negative, it empties. The magnitude of the net rate yields the time for a full tank (if filling) from empty.

Given Data / Assumptions:

• A = 1/25 tank/min.
• B = 1/40 tank/min.
• C = −1/30 tank/min.

Concept / Approach:
Net rate r = 1/25 + 1/40 − 1/30. If r > 0, time to fill = 1/r minutes.

Step-by-Step Solution:

Verification / Alternative check:
31.58 min * 19/600 ≈ 1 tank, confirming.

Why Other Options Are Wrong:
Given numeric options do not match 600/19 minutes; therefore “None of these.”

Common Pitfalls:
Arithmetic with mixed denominators or assuming integer results. The exact fraction 600/19 is correct.

Final Answer:
None of these (net fill time = 600/19 minutes ≈ 31.58 min)