SOLUTION: A candle is 8 in. tall after burning 2 hrs. After 4 hrs it is 5 1/2 in. tall. Write a linear equation to model the height y of the candle after x hours. After how many hours wil

Question 814097: A candle is 8 in. tall after burning 2 hrs. After 4 hrs it is 5 1/2 in. tall. Write a linear equation to model the height y of the candle after x hours. After how many hours will the candle be 4 inches tall?
Found 2 solutions by josgarithmetic, MathTherapy:
Answer by josgarithmetic(39617) (Show Source): You can put this solution on YOUR website!
The description gives two data points, (x,y) where x is time and y is tallness of the candle. These two points are (2, 8) and (4, 5.5). These two points define a line in variables x and y.

That desired line:
All using slope-intercept form, ;

Use either point from the problem description,

The equation for the line is ;
Again, y is tallness or height of the candle in inches, and x is time in hours after burning (at the wick). The question is about how much time to burn to become 4.5 inches. JUST SOLVE THE EQUATION FOR x, and let y=4.5.

The whole situation could have been analyzed using x for tallness and y for burn time, but normally, most people would use time as an independant variable and something else as the dependant variable.
Answer by MathTherapy(10552) (Show Source): You can put this solution on YOUR website!
A candle is 8 in. tall after burning 2 hrs. After 4 hrs it is 5 1/2 in. tall. Write a linear equation to model the height y of the candle after x hours. After how many hours will the candle be 4 inches tall?

Linear equation: , with x being time (in hours), and y being height

After substituting 4 for y in the above linear equation, it's seen that it'll take hours, or to reach 4".

You can do the check!!

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