Question

Chalk contains $10\%$ calcium, $3\%$ carbon and $12\%$ oxygen, Find the amount of carbon and calcium (in grams) in $2\frac{1}{2}$ kg of chalk.

Answer 1

We have,
Percentage of calcium in chalk $=10\%$
Percentage of carbon in chalk $=3\%$
Percentage of oxygen in chalk $=12\%$
$\because$ Weight of chalk $=2\frac{1}{2}kg=\frac{5}{2}kg$
$=2.5\times 1000g=2500gm[\because 1kg=1000g]$
Thus, the Amount of carbon in chalk $=3\%$ of $2500g$
$=\frac{3}{100}\times 2500$
$=25\times 3$
$=75g$
Thus, amount of calcium in chalk $=10\%$ of $2500g$
$=\frac{10}{100}\times 2500$
$=10\times 25$
$=250g$

Hence, the amount of carbon and calcium are $75g$ and $250g$ respectively.