Chapter 7.8, Problem 1ST

To determine

To find: the liters of water that is evaporated from 50 liter of 10 percent salt solution to the 20 percent salt solution.

Answer to Problem 1ST

The $\text{25L}$ of water must be evaporated to give a salt solution of $\text{20\%}$ from a $\text{10\%}$ salt solution.

Explanation of Solution

Given:

Concept used:

  $\text{Solution=50L}$.

While evaporating:

  $\text{10\%}$ salt solution is producing $\text{20\%}$ salt solution.

Calculation:

According to the given data:

  $\text{Solution=50L}$.

While evaporating:

  $\text{10\%}$ salt solution is producing $\text{20\%}$ salt solution.

Mathematically:

Let $\text{x}$ is the liters of water evaporated during the conversion:

  $\text{10\%}\left(\text{50}\right)\text{=20\%}\left(\text{50-x}\right)$.

  $\text{0}\text{.1}\left(\text{50}\right)\text{=0}\text{.2}\left(\text{50-x}\right)$.

  $\text{5=10-0}\text{.2x}$

Multiplying and distributing the terms:

  $\text{-5=-0}\text{.2x}$.

  $\text{50=2x}$.

Dividing both side by $\text{2}$ :

  $\text{x=25}$.

Hence the $\text{25L}$ of water must be evaporated to give a salt solution of $\text{20\%}$ from a $\text{10\%}$ salt solution.

New price= $\$40.12$.

For increasing in percentage use the Formula:

  $\frac{\text{New price-Oirginal price}}{\text{Original price}}\text{=\%Increase}\text{.}$

  $\frac{40.12-34.00}{34.00}=\frac{6.12}{34}=0.18=18\%$.

Hence the increase of price in percentage is $18\%$ of original price.