Question

A 13-inch candle is lit and steadily burns until it is burned out.

a. As the burned length of the candle increases from 3 to 7.5 inches, the remaining length of the candle varies from _____inches to _____ inches


b. Suppose b represents the burned length of the candle in inches (or the number of inches that have burned from the candle since it was lit).

Write an expression in terms of b that represents the remaining length of the candle (in inches). ________

Answer 1

a. The remaining length of the candle varies from 10 inches to 5.5 inches

b. Remaining Length = 13 - b

Explanation:

b.

The remaining (unburnt) length of the candle must be equal to the difference between total length of the candle and the burnt length of the candle. So, the expression for the remaining length can be written as:

Remaining Length = Total Length - Burnt Length

where,

Total length = 13 inch

Burnt Length = b

Therefore,

Remaining Length = 13 - b

b.

Now, we use the same expression for:

burned length = 3 inches

Therefore,

Remaining Length = 13 inches - 3 inches

Remaining Length = 10 inches

Now, for

burned length = 7.5 inches

Therefore,

Remaining Length = 13 inches - 7.5 inches

Remaining Length = 5.5 inches

Hence,

The remaining length of the candle varies from 10 inches to 5.5 inches