Posted by Brad Paul on October 30, 2002 at 18:31:31:
In Reply to: Length of Time posted by RD on October 30, 2002 at 17:47:44:
: Two candles are in a building. One is red and the other is blue. The candles are the same height, but the red is slightly thicker. The red burns out in 3 hours and the blue 2. After an amount of time the length of the red left unburned was twice that of the blue. A person who was in the building had a watch but it stopped, and there was no other clock in the building. How long was the person there?
: Please show step by step. Thanks for your help.
How tall are the two candle? I don't know so let me call their height h.
What is the rate at which the red candle burns?
Where tred is the time it takes for the red candle to burn out.
What is the rate at which the blue candle burns?
Where tblue is the time it takes for the blue candle to burn out.
At some time t we note that:
"length of the red left unburned was twice that of the blue"
What is the height of the red candle after time t?
What is the height of the blue candle after time t?
Write an equation for what was seen:
2(h-h/tred t)=(h-h/tblue t)
solve for t
Post a Followup