Question

Elio makes candles that are 14cm. Each candle burns 8 hours before going out. He is wondering how many hours a 21 cm tall candle can burn for. He assumes that the relationship between the height of a candle and number of hours it burns (h), is proportional.

Answer 1

Elio is right in assuming the relationship between the height and the hours it burns is proportional.

Find the unit rate

14 ÷ 8 = 1.75 cm/h

Divide

21 ÷ 1.75 = 12

You can set this up as an algebraic equation to check the answer.

If the candle is 21 cm tall, it will burn for 12 hours.