Wick Math Problem?

Question

A straight, vertical 43-inch wick was lit from the top and burned downward at the constant rate of 1.5 inches per hour, Three hours later, the bottom of the wick also was lit and it burned upward at the constant rate of 4 inches per hour . How many total inches ha dth etop of the wick burned down when the burning ends met?

Answer 1

43-(3*1.5)=38.5inches (length of wick after 3 hrs)
38.5/(1.5+4)=7hrs (time to burn rest of wick)

(7*1.5)+(3*1.5)=15 inches the top of the wick burns in total

Answer 2

[19]
Before the bottom of the wick was lit,3*1.5 or 4.5 inches has already burnt from the top
remaining length
=43-4.5
=38.5 inches
when both ends are lit,the tape burns @(1.5+4) or 5.5 inches per hour
Time taken to burn 38.5inches
=38.5/5.5
=7 hours
Therefore the top end burns for a total period of 10 hrs and so burns 10*1.5 or 15 inches

Answer 3

After three hours, the wick is 43 - ( 3 ) ( 1.5 ) = 38.5 inches long. After lighting the bottom, the length is reduced at a rate of 1.5 + 4.0 = 5.5 inches per hour, so the flames meet 38.5 / 5.5 = 7 hours later. So after ten hours the top flame has burned 15 inches.