Answer:
[tex]Time = 560\ mins[/tex]
Step-by-step explanation:
Given
[tex]Candles = 2[/tex] --- candles melted
[tex]Divisions = 12[/tex]
[tex]Time = 4\ hrs[/tex] --- time to melt
Required
The time since the first was lit
If 1 candle melts in 4 hours, 2 candles will melt in 8 hours.
i.e.
[tex]x = Candles * Time[/tex]
[tex]x = 2 * 4hrs[/tex]
[tex]x = 8hrs[/tex]
For the 3rd candle that has melted, 4 inches
First, calculate the fraction that melt
[tex]Fraction = \frac{Melt}{Division}[/tex]
[tex]Fraction = \frac{4}{12}[/tex]
[tex]Fraction = \frac{1}{3}[/tex]
The time to melt is:
[tex]y = Fraction * Time[/tex]
[tex]y= 4 * \frac{1}{3}[/tex]
[tex]y= \frac{4}{3}hrs[/tex]
So, the required time is:
[tex]Time = x + y[/tex]
[tex]Time = 8hrs + \frac{4}{3}hrs[/tex]
Convert to minutes
[tex]Time = 8*60mins + \frac{4}{3}*60mins[/tex]
[tex]Time = 480mins + 80mins[/tex]
[tex]Time = 560\ mins[/tex]