SOLUTION: two candles of equal length are lit at the same time. one candle takes 6 hours to burn out and the other takes 3 hours. After how much time will the slower burning candle be exactl

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Question 1065529: two candles of equal length are lit at the same time. one candle takes 6 hours to burn out and the other takes 3 hours. After how much time will the slower burning candle be exactly twice as long as the faster burning one?

Answer by ikleyn(52788) About Me  (Show Source):
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two candles of equal length are lit at the same time. one candle takes 6 hours to burn out and the other takes 3 hours.
After how much time will the slower burning candle be exactly twice as long as the faster burning one?
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Faster candle rate of burning is L%2F3 of its length per hour.

Slower candle rate of burning is L%2F6 of its length per hour.

The length of the remaining part for the faster candle is L+-+%28L%2F3%29%2At after t hours.

The length of the remaining part for the slower candle is L+-+%28L%2F6%29%2At after t hours.

The question asks about time t when Slower(t) = 2*Faster(t), or

2%2A%28L+-+%28L%2F3%29%2At%29 = %28L+-+%28L%2F6%29%2At%29 .


To solve for t, multiply both sides by 6%2FL. You will get

12%2A%281-t%2F3%29 = 6%2A%281-t%2F6%29,   or

12 - 4t = 6 - t  --->  12 - 6 = 4t - t  --->  6 = 3t  --->  t = 2.

Answer. After 2 hours.

If you have questions or want to say "thanks", then please mention the ID number of this problem (# 1065529) in your response.