Question

Two candles are of different lengths and thicknesses. The short and the long ones can burn respectively for 3.5 hour and 5 hours. After burning for 2 hour, the lengths of the candles become equal in length. What fraction of the long candle’s height was the short candle initially?

• A. $\frac{2}{7}$
• B. $\frac{5}{7}$
• C. $\frac{3}{7}$
• D. $\frac{4}{5}$

Answer 1

The correct option is B

$\frac{5}{7}$

Let the lengths are $l_1$ and $l_2$ and thickness are $x_1$ and $x_2$

$l_1$ = 3.5 hr and $l_2$ = 5 hr

$l_1$ - 2$\times$$\frac{l_1}{3.5}$ = $l_2$ - 2$\times$$\frac{l_2}{5}$

$\frac{3.5l_1-2l_1}{3.5}$ = $\frac{5l_2-2l_2}{5}$

$\frac{l_1}{l_2}$ = $\frac{5}{7}$