How much of bottle B must be added to all of…

How much of bottle B must be added to all of bottle A to make a 40% solution?

Question 65

MediumOriginal question

A laboratory has 40 litres of a 25% acid solution in bottle A and a large supply of a 60% acid solution in bottle B.

How much of bottle B must be added to all of bottle A to make a 40% solution?

20 litresCorrect answerYour answer30 litresCorrect answerYour answer40 litresCorrect answerYour answer

\frac{160}{3}

litresCorrect answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer B

Correct answer: B

A : B $= (60 - 40) : (40 - 25) = 20 : 15 = 4 : 3$ .
For 40 litres of A, $40 \times \frac{3}{4} = 30$ litres of B. Check: $\frac{10 + 18}{70} = 40\%$ .

Worth noting

53.3 litres uses the ratio the wrong way round, $3 : 4$ .

Ten questions from Alligation & Mixtures, at your own pace.

Ten questions from Alligation & Mixtures, at your own pace.