How would I write this problem as a Linear Equation?

Question

How would I write this word problem in Slope/Intercept form:

"A candle has a height of 90.0 mm before it is lit on fire. Once the candle is burning, it burns down at a rate of -1.5 mm/sec."

Thank you in advance!

Answer 1

Candle Length = -1.5*t + 90

Y = mx + c

m = -1.5mm/s

x = t = time in seconds

c = 90 mm = beginning height of the candle

BTW, in general, when ever you are faced with such a problem, try to isolate it into 4 factors:

(1) A variable that is changing independently e.g., time

(2) A variable that is being affected by #1 e.g., candle height

(3) Rate of change - how fast is candle height changing over time, and

(4) What was the initial magnitude or amount of #2

Then you can convert it into an equation of the y = mx + c form

#2 = (#3 x #1) + #4

Does this make sense? Good luck.

Answer 2

For t in seconds and height in mm:

height = -1.5t + 90

At time zero, the height is the initial 90 mm. Each unit increase in time will decrease the height by 1.5 mm.

Answer 3

y=-3/2x+60

Answer 4

Let h represent the height of the candle and s the elapsed time in seconds since it was lit. The formula is then

h = 90 - 1.5s