Two candles of equal heights but different thicknesses are lit.
The first burns off in 8 hours and the second in 10 hours.
How long after lighting, in hours, will the first candle be half the height of the second candle?
The candles are lit simultaneously and each burns at a constant linear rate.

One way to solve this problem is by putting the two candles onto a graph. You can then algebraically solve these by comparing the slopes of the graphs, and locating the point at which the first candle is half the height of the second. The formulae can get slightly complicated, but if you know your stuff you'll discover that the answer is 6 hours, 40 minutes.

Asked by Ben Jenkins · Last updated 3 years ago · 614 views · SOURCE