Question

When lit, a candle loses 8% of the unlit candle every hour. Janet lit a candle with an original height of 5 inches. Until the candle has been burning for at least ___ hours, the height of her candle will be more than four inches.

Please help! This was on a test but it’s confusing to me!

Answer 1

2.5 hours

Explanation:

We are given that

Original height of candle=5 in

Every hour candle loses =8% of 5 in=0.4

According to question

`5-0.4x>4`

Subtract 4 from both sides we get

`5-4-0.4x>0`

`1-0.4x>0`

`-0.4x>-1`

`0.4x<1`

Divide by 0.4 on both sides

`x<(1)/(0.4)`

`x<2.5`

x=2.5 hours

Until the candle has been burning for at least 2.5 hours, the height of her candle will be more than four inches.