Question

A mixture of petrol and kerosene weighing 5 kg contains 5% kerosene. How much more kerosene (approx.) must be added into it to make it 10%?

Accepted Answer

B. Initial kerosene in 5000 g mixture = $5\% 	imes 5000 = 250$ g. Let $x$ g of kerosene be added. $$\frac{250 + x}{5000 + x} = \frac{10}{100}$$ $$2500 + 10x = 5000 + x \implies 9x = 2500 \implies x \approx 277.77 	ext{ g} \approx 275 	ext{ g.}$$

Mixture concentration adjustment

Explanation

Practise this under exam conditions