__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

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**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

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