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📊 Math
Q. A pipe can fill a tank in 25 hours. After 5 hours, a leak develops and the tank gets filled in 30 hours total. In how many hours can the leak empty the full tank?
  • (A) 75 hours
  • (B) 50 hours
  • (C) 60 hours
  • (D) 100 hours
💬 Discuss
✅ Correct Answer: (A) 75 hours

Explanation: Leak rate = 1/25 − 1/30 = 1/75.

📊 Math
Q. Pipe A can fill a tank in 20 hours and pipe B can empty it in 40 hours. If both are opened together, how long will it take to fill half the tank?
  • (A) 10 hours
  • (B) 20 hours
  • (C) 30 hours
  • (D) 40 hours
💬 Discuss
✅ Correct Answer: (B) 20 hours

Explanation: Net rate = 1/20 − 1/40 = 1/40 → half tank in 20 hours.

📊 Math
Q. Three pipes fill a tank in 12, 18 and 36 hours respectively. How long will they take to fill the tank together?
  • (A) 6 hours
  • (B) 8 hours
  • (C) 9 hours
  • (D) 12 hours
💬 Discuss
✅ Correct Answer: (B) 8 hours

Explanation: 1/12+1/18+1/36 = 1/8.

📊 Math
Q. A tank has two inlet pipes and one outlet pipe. Inlet pipes fill the tank in 10 and 20 hours, outlet empties in 40 hours. How long will the tank take to fill?
  • (A) 8 hours
  • (B) 10 hours
  • (C) 13.33 hours
  • (D) 20 hours
💬 Discuss
✅ Correct Answer: (B) 10 hours

Explanation: Net rate = 1/10 + 1/20 − 1/40 = 1/10.

📊 Math
Q. Pipe A can fill a tank in 6 hours. Pipe B empties it in 18 hours. If A works for 3 hours and then both are opened, how long will the tank take to fill completely?
  • (A) 4 hours
  • (B) 5 hours
  • (C) 6 hours
  • (D) 7 hours
💬 Discuss
✅ Correct Answer: (C) 6 hours

Explanation: A fills half in 3 hrs. Remaining filled at rate (1/6−1/18)=1/9 → total = 6 hrs.

📊 Math
Q. Two pipes fill a tank in 30 hours and 40 hours. If both are opened together for 10 hours and then the slower pipe is closed, how long will the faster pipe take to fill the remaining tank?
  • (A) 10 hours
  • (B) 12 hours
  • (C) 15 hours
  • (D) 20 hours
💬 Discuss
✅ Correct Answer: (B) 12 hours

Explanation: Work in 10 hrs = 7/120 → remaining = 113/120 → faster pipe (1/30) takes ≈12 hrs.

📊 Math
Q. Pipe A fills a tank in 3 hours and pipe B empties it in 6 hours. If both are opened together, how long will it take to fill the tank?
  • (A) 3 hours
  • (B) 4 hours
  • (C) 6 hours
  • (D) No filling
💬 Discuss
✅ Correct Answer: (C) 6 hours

Explanation: Net rate = 1/3 − 1/6 = 1/6.

📊 Math
Q. A pipe can fill a tank in 50 hours. Due to a leak, it is filled in 75 hours. In how many hours can the leak empty the full tank?
  • (A) 150 hours
  • (B) 100 hours
  • (C) 75 hours
  • (D) 50 hours
💬 Discuss
✅ Correct Answer: (A) 150 hours

Explanation: Leak rate = 1/50 − 1/75 = 1/150.

📊 Math
Q. A pipe can fill a tank in 12 hours. How much part of the tank is filled in 1 hour?
  • (A) 1/10
  • (B) 1/12
  • (C) 1/6
  • (D) 1/8
💬 Discuss
✅ Correct Answer: (B) 1/12

Explanation: If tank fills in 12 hours, then 1 hour work = 1/12.

📊 Math
Q. A pipe fills a tank in 20 hours. Another pipe empties it in 30 hours. If both are opened together, in how many hours will the tank be filled?
  • (A) 40 hours
  • (B) 50 hours
  • (C) 60 hours
  • (D) 120 hours
💬 Discuss
✅ Correct Answer: (C) 60 hours

Explanation: Net rate = 1/20 − 1/30 = 1/60.

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