Problema Solution
Una recently purchased two boxes of ten-inch candles -- one box from a discount store, and the other from an expensive boutique. It so happens that the inexpensive candles last only three hours each, while the expensive candles last five hours each. One evening, Una hosted a dinner party and lighted two candles -- one from each box -- at 7:30 PM. During desert, a guest noticed that one candle was twice as long as the other. At what time was this observation made?
Answer provided by our tutors
Let 't' represent the time after the candles were lit
10/3 in per hour is the rate o the inexpensive candles
10/5 = 2 in per hour is the rate of the expensive cadles
2(10 - t*(10/3)) = 10 - t*(10/5)
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t = 15/7 hr
t = 2 hr 1*60/7 min
t = 2 hr 9 min
2 hr 9 min after 7:30 PM is 9:39 PM
This observation was made at 9:39 PM.