expression for word problem

Question

A candle burns for 2 minutes and is 8 inches long the same candle is 7 and one quarter long after 3 minutes assume the candle will burn at same rate.

Answer 1

at 2 min it was 8"

at 3 min it was 7.25"

 

so the candle burns at .75" per minute.

 

 

 

Answer 2

Hi Wesley,

 

I could not see any question in this. But I assume that you may want to know either the rate of burning or the total initial height of candle or how long it would take to burn the entire candle.

 

Assume that at time t=0 length of candle is `x`

 Given at t=2 minutes, length is 8 inches

at t= 3 minutes, length is 7.25 inches

 

So the rate of burning of the candle or the rate at which the length of candle is decreasing = decrease in length / time duration

= (8-7.25)inches/(3-2) minutes

= 0.75 inches/minute

 

to find the initial length of the candle, use this formula for the times t=0 and t=2 minutes

 

the rate of change is same (given)

 

so, 0.75= (x-8)/(2-0)

 

solving this x= 9.5 inches

 

suppose it takes t` seconds to fully burn the candle

implies at t=t` length of the candle is 0 inches

 

so t`= .75 * 9.5 = 7.125 minutes or 7.13 minutes.

 

I hope this would help you.