Question

A scientist mixes water ( containing no salt) with a solution that contains 40% salt. She wants to obtain 120 ounces of a mixture that is 30% salt. How many ounces of water and how many ounces of the 40% salt solution should she use?Water: __ouncesSalt solution: __ounces

Answer 1

$\begin{gathered} \text{ Total onces of mixture = 120 ounces} \\ \text{This 120 ounces contains 30\% salt} \\ \text{Amount of salt present in the product = 30\% of 120 = }\frac{30}{100}\text{ x 120 = 36 ounces} \end{gathered}$$\begin{gathered} \text{ Amount of water present in the product = 120 - 36 = 84 ounces} \\ \end{gathered}$$\begin{gathered} \text{ Let y be the amount of salt solution used} \\ \text{The solution contains 40\% salt , this implies } \\ 40\text{ \% of Y = 36} \\ 0.4y=36 \\ y=\frac{36}{0.4} \\ y=90\text{ ounces of salt solution} \\ \\ \text{Amount of water}=\text{ 120 - 90 = 30 ounces of water} \end{gathered}$

Hence, the answer is

Water: _30_ounces



Salt solution: _90_ounces​