You can
put this solution on YOUR website!A red candle is 45 cm tall and burns 3 cm per hour, a white candle is 30 cm tall and burns 1-1/2 cm per hour, how tall will each candle be after 1 hour, 3 hours, 5 hours and 12 hours?
:
What is the formula for calculating each candle's height at each time
Let t = time in hrs
:
Red: Candle ht = 45 - 3t
White: Candle ht = 30 - 1.5t
:
Substitute 1, 3, 5 and 12 in each equation
:
Example: using the Red candle burning 12 hrs
ht = 45 - 3(12)
ht = 45 - 36
ht = 9 cm
:
:
which candle lasts longer?
Red
45 - 3t = 0
-3t = -45
t = -45/-3
t = +15 hrs duration of the Red candle
:
White
30 - 1.5t = 0
-1.5t = -30
t = -30/-1.5
t = 20 hrs duration of the white candle
:
:
Will the red and white candles ever be the same height at the same time if started at the same time?
:
White ht = Red ht
30 - 1.5t = 45 - 3t
3t - 1.5t = 45 - 30
1.5t = 15
t = 15/1.5
t = 10 hrs they will be equal
:
You can determine that height that is, substitute 10 for t in either equation
and solve for ht
