A friend and I are getting different answers for the same problem. I would like to know which method for solving is correct, and why the other one does not work.
The Problem:
A candle weighs 12 oz.
It burns for 5 hours and .8 oz are consumed.
How long will it take for the remainder of the candle to burn?
I set up my formula this way:
(12 / 12) - (.8 / 12) = (11.2 / 12), or .94, that's how much candle you still have left
therefore, .06 is the percentage which burned in 5 hours
so you set up a purportional equation
(5 hrs./ .06) = (x / .94), where x = how long it will take the remainder to burn, assuming the same rate
5 hrs. /.06 * .94 = x
78.333 hrs. = x
==================
My friend figures it this way:
Total estimated burn time = (initial mass)(duration of test burn)/(change in mass)
so,
(12 oz)(5 hours) = 60 divided by .8 = 75
[/u]
The Problem:
A candle weighs 12 oz.
It burns for 5 hours and .8 oz are consumed.
How long will it take for the remainder of the candle to burn?
I set up my formula this way:
(12 / 12) - (.8 / 12) = (11.2 / 12), or .94, that's how much candle you still have left
therefore, .06 is the percentage which burned in 5 hours
so you set up a purportional equation
(5 hrs./ .06) = (x / .94), where x = how long it will take the remainder to burn, assuming the same rate
5 hrs. /.06 * .94 = x
78.333 hrs. = x
==================
My friend figures it this way:
Total estimated burn time = (initial mass)(duration of test burn)/(change in mass)
so,
(12 oz)(5 hours) = 60 divided by .8 = 75
[/u]