Dr. Lal And Jain Solutions for Exercise 1: Solved Examples

A tea merchant blends two types of tea costing $Rs. 15 per kg$ and $Rs. 20 per kg$ each, respectively. In what ratio should these two types of tea be mixed so that the resulting mixture costs $Rs. 16.50 per kg$?

In what ratio should water be mixed in the spirit so that there is a gain of $16\frac{2}{3}\%$ when the resulting mixture is sold at the C.P. of the spirit only?

$21 \mathrm{litre}$ of a mixture of $95\%$ purity is obtained when two solutions are mixed. If the purity of one solution is $90\%$ and the purity of the other be $97\%$, then how much solution of purity $97\%$ is taken?

$9 \mathrm{litre}$ are drawn from a cask full of water and it is then filled with milk. $9 \mathrm{litre}$ of the mixture are drawn and the cask is again filled with milk. The quantity of water now left in the cask is to that of the milk in the cask is $16:9$. How much mixture does the cask hold?

A mixture of $20 kg$ of spirit and water contains $10\%$ of water. How much water must be added to increase the percentage of water to $25\%$?

A trader bought $50 kg$ of wheat at $Rs.7 per kg$ and $20 kg$ of wheat at $Rs. 8 per kg$. He mixed both and sold the mixture at$Rs.10 per kg$. What is the profit?

Alok bought $30 kg$ of rice at $Rs. 8.50 per kg$ and $20 kg$ of rice at$Rs. 8.00 per kg$. If he has to make a $20\%$ profit, at approximately what rate per kg should he sell his rice?