Question

A scientist needs 270 milliliters of a 20% acid solution for an experiment. The lab has available a 25% and a 10% solution. How many milliliters of the 25% solution and how many milliliters of the 10% solution should the scientist mix to make the 20% solution?

Answer 1

Given:

A scientist has 5% and a 10% acid solution in his lab.

He needs 270 milliliters of a 20% acid solution.

To find the amount of 25% solution and how many milliliters of the 10% solution should the scientist mix to make the 20% solution:

Here,

The dearer percentage is 25%.

The cheaper percentage is 10%.

The mean percentage is 20%.

Using the mixture and allegation method,

The ratio of the litters of cheaper (10% solution) to dearer value (25% solution) is,

`\begin{gathered} (\text{Dearer value-mean): (Mean-Ch}eaper\text{ value)} \\ (25-20)\colon(20-10) \\ 5\colon10 \\ 1\colon2 \end{gathered}`

So, the number of liters to be taken from 10% solution is,

`(1)/(3)*270=90\text{ liters}`

So, the number of liters to be taken from 25% solution is,

`(2)/(3)*270=180\text{ liters}`

Hence, the answer is