SOLUTION: I have a work problem: Laura lights a candle in her kitchen. The candle is burning at a rate of .5 inches per hour. After 5 minutes the candle is 3.5 inches tall. I need to know wh

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Question 1019767: I have a work problem: Laura lights a candle in her kitchen. The candle is burning at a rate of .5 inches per hour. After 5 minutes the candle is 3.5 inches tall. I need to know what equation I use to figure out the height of the candle.
Found 3 solutions by josgarithmetic, josmiceli, MathTherapy:
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Try to identify the job. What is doing the job? Maybe, say the flame is doing a job of consuming length of the candle.

You want to think with RT=L to relate rate, time, length.

Rate is 0.5%28inches%2Fhour%29.
Some data is time 1%2F12 hours, x-3.5 inches consumed. Think how that makes sense, before continuing.

...

The situation as equation including the units of measure,
0.5%28inches%2Fhour%29%2A%281%2F12%29%2Ahour=%28x-3.5%29%2Ainches, using x for the length of the candle originally.

And then just the numbers without the units,
0.5%281%2F12%29=x-3.5
which should be easy to solve.

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +h+ = the initial height of the candle
I can say:
[ final height ] = [ rate of decrease] + [ initial height ]
+h+=+-.5%2Ah+%2B+h%5B0%5D+
--------------------
Convert minutes to hrs
+5%2F60+=+1%2F12+ hrs
[ .5 in/hr ] x [ hrs ] = [ inches ]
+%281%2F2%29%2A%281%2F12%29+=+1%2F24+ height decrease after 5 min
-------------------------
+h%5B0%5D+=+3.5+%2B+1%2F24+
+h%5B0%5D+=+3.5+%2B+.04167+
+h%5B0%5D+=+3.54167+
-----------------
+h+=+-.5t+%2B+3.54167+
This should give the height after +t+ min
--------------
check:
+t+=+1%2F12+
+h+=+-1%2F24+%2B+3.54167+
+h+=+-.041667+%2B+3.54167+
+h+=+3.5+
---------------
Here's the plot:
Hope I got it
+graph%28+400%2C400%2C+-5%2C+12%2C+-5%2C+7%2C+-.5x+%2B+3.54167+%29+

Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!

I have a work problem: Laura lights a candle in her kitchen. The candle is burning at a rate of .5 inches per hour. After 5 minutes the candle is 3.5 inches tall. I need to know what equation I use to figure out the height of the candle. 
With H being height of the candle after t minutes, equation is: