Multiple choice general knowledge math & puzzles

A swimming pool has four faucets. The first can fill the entire pool with water in two days, the second – in three days, the third – in four days, and the last one can fill the pool in 6 hours. How long will it take(approximately) to fill the pool using all 4 faucets together?

  1. 5 hr 15 min

  2. 6 hr

  3. 4 hr 43 min

  4. 3 hr
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Convert all rates to per-hour basis. First: 1 pool/48 hours = 1/48 pool/hour. Second: 1/72 pool/hour. Third: 1/96 pool/hour. Fourth: 1/6 pool/hour. Combined rate: 1/48 + 1/72 + 1/96 + 1/6 = (6+4+3+48)/288 = 61/288 pool/hour. Time = 1 / (61/288) = 288/61 hours ≈ 4.72 hours = 4 hours + 0.72×60 min = 4 hours 43.2 minutes, which rounds to approximately 4 hr 43 min.

AI explanation

Convert each faucet's rate to pool-per-hour: faucet 1 fills 1/2 pool/day = 1/48 per hour, faucet 2 = 1/3 pool/day = 1/72/hr, faucet 3 = 1/4 pool/day = 1/96/hr, faucet 4 fills the whole pool in 6 hours = 1/6/hr. Summing (common denominator 288): 6/288 + 4/288 + 3/288 + 48/288 = 61/288 pool per hour. Time to fill = 288/61 ≈ 4.72 hours ≈ 4 hr 43 min, matching the given answer. The other options don't satisfy this combined-rate equation.

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