12
Two taps X and Y can fill a tank in 15 hours and 20 hours respectively. If the two taps are opened at 2 p.m., then at what time (in p.m.) should the tap X be closed to completely fill the tank at exactly 2 a.m.?
- A8
- B7
- C9
- D10
Answer not set
Discussion 1
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0
CCommunity
From 2 pm to 2 am = 12 hours
Let tap X will closed after x hours.
According to the question,
⇒ x/15 + 12/20 = 1
⇒ (4x + 36) = 60
⇒ 4x = 24
⇒ x = 6 hours
∴ the tap X should be closed at (2 pm + 6 h =) 8 pm
Let tap X will closed after x hours.
According to the question,
⇒ x/15 + 12/20 = 1
⇒ (4x + 36) = 60
⇒ 4x = 24
⇒ x = 6 hours
∴ the tap X should be closed at (2 pm + 6 h =) 8 pm