Two candles of the same height are lit at the same time. The first is consumed in 4 hours and the second in 3 hours. Assuming that each candle burns at a constant rate, in how many hours after being lit is the first candle twice the height of the second?
The first candle burns at rate 1 candle / 4 hrs
multiply rate * time to get amount burned 1/4 t
the amount REMAINING is 1 candle - 1/4 t = 1- 1/4t
Similarly for the SECOND candle, the amount remaining is 1 - 1/3 t
We want the time for the length of first to be 2 times length of second:
1-1/4t = 2 * (1 - 1/3t) solve for t = ........ hrs