SOLUTION: After 11 hours of burning, a candle has a height of 26.8 centimeters. After 23 hours of burning, its height is 24.4 centimeters. What is the height of the c

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: After 11 hours of burning, a candle has a height of 26.8 centimeters. After 23 hours of burning, its height is 24.4 centimeters. What is the height of the c      Log On


   

Question 1071964: After
11
hours of burning, a candle has a height of
26.8
centimeters. After
23
hours of burning, its height is
24.4
centimeters. What is the height of the candle after
20
hours?
Found 2 solutions by josgarithmetic, ikleyn:
Answer by josgarithmetic(39621) About Me  (Show Source):
You can put this solution on YOUR website!
x time in hours
y candle height
Description gives two points (x,y):
(11,26.8) and (23, 24.4).

Slope, -0.2;

y-26.8=-0.2%28x-11%29
highlight%28y=-0.2x%2B29%29

Question is, what is candle height, y, after 20 hours?
Let x=20 and evaluate y.

Answer by ikleyn(52817) About Me  (Show Source):
You can put this solution on YOUR website!
.
The linear interpolation between 11 hours and 23 hours gives the formula for the candle height


h(t) = 26.8+-+%28%2826.6-24.4%29%2F%2823-11%29%29%2A%28t-11%29 =  26.8+-+%282.4%2F12%29%2A%28t-11%29 = 26.8+-+0.2%2A%28t-11%29,


where t is the time of burning in hours (between 11 and 20).


Then h(20) = 26.8+-+0.2%2A%2820-11%29 = 25 cm.

Answer. 25 centimeters.