Question

The wheat sold by a grocer contained 10% low quality wheat. What quantity of good quality wheat should be added to 150 kg of wheat, so that the percentage of low quality wheat becomes 5%?

• A. 150 kg
• B. 135 kg
• C. 50 kg
• D. 85 kg
• E. None of these

Answer 1

The correct option is A 150 kg

Here, total weight of the mixture
=150 kg
Quantity of low quality weight $=150\times \frac{10}{100}$
=15 kg
Now, $\frac{15}{150+x}\times 100=5$
or 1500=750+5x
or $x=\frac{750}{5}\Rightarrow x=150kg$
Alternate Method
When percentage value get halved, then quantity of the mixture get doubled.
$\therefore 150\times 2=300$ kg, so 150 kg more wheat should be added.