Question

A candle looses 10% of its length in every 60 seconds. If the height of the candle is 20 cm, find what will be its length after 4 minutes?
1. 14.58 cm
2. 13.122 cm
3. 14.222 cm
4. 13.48 cm

Answer 1

Correct Answer - Option 2 : 13.122 cm

Given:

Height of candle = 20 cm

Height lost in 60 seconds = 10% of present height

Concept:

Since the candle loses its 10% length after 60 seconds, so it will lose its length 4 times in 4 minutes.

Calculation

Height of the candle after 240 seconds = 20 × (9/10) × (9/10) × (9/10) × (9/10)

= 13.122 cm