7.Two candles of the same height are lighted at thesame time. The firs

1.	7.Two candles of the same height are lighted at thesame time. The first is consumed in 4 hours andthe second in 3 hours. Assuming that each candleburns at a constant rate, in how many hours aftietbeing lighted, was the first candle twice the beigihtof the second?
Answer» Let the height of candles = hFirst candle consumed in 4 hoursSecond candle consumed in 3 hours Burning rate of first candle = h/4Burning rate of second candle = h/3 Let after x hours height of second candle is y and height of first candle is 2y Then, y = h - xh/3.......(1)2y = h - xh/4.....(2) 2(h - xh/3) = h - xh/42h - h = 2xh/3 - xh/4h = (8xh - 3xh)/12x = 12/5 = 2.5 Therefore, after 2.5 hours height of first candle is twice the height of second candle

7.Two candles of the same height are lighted at thesame time. The first is consumed in 4 hours andthe second in 3 hours. Assuming that each candleburns at a constant rate, in how many hours aftietbeing lighted, was the first candle twice the beigihtof the second?

Answer»

Let the height of candles = hFirst candle consumed in 4 hoursSecond candle consumed in 3 hours

Burning rate of first candle = h/4Burning rate of second candle = h/3

Let after x hours height of second candle is y and height of first candle is 2y

Then, y = h - xh/3.......(1)2y = h - xh/4.....(2)

2(h - xh/3) = h - xh/42h - h = 2xh/3 - xh/4h = (8xh - 3xh)/12x = 12/5 = 2.5

Therefore, after 2.5 hours height of first candle is twice the height of second candle