O RATIONAL EXPRESSIONS
Word problem on proportions: Problem type 2
A certain drug is made from only two ingredients: compound A and compound B. There are 5 millititers of compound A used for every 6 millititers of compound B. If a chemist wants to make 836 millititers of the drug, how many millititers of compound $B$ are needed?
milliliters of compound B

Step 1 ：The problem is asking for the amount of compound B needed to make 836 milliliters of the drug. We know that the ratio of compound A to compound B is 5:6. This means that for every 5 milliliters of compound A, we need 6 milliliters of compound B.

Step 2 ：We can set up a proportion to solve for the unknown amount of compound B. Let's denote the total amount of the drug as \(total\_drug\), the ratio of compound A as \(ratio\_A\), the ratio of compound B as \(ratio\_B\), and the total ratio as \(total\_ratio\).

Step 3 ：Given that \(total\_drug = 836\), \(ratio\_A = 5\), and \(ratio\_B = 6\), we can calculate \(total\_ratio\) as the sum of \(ratio\_A\) and \(ratio\_B\), which is 11.

Step 4 ：Then, we can calculate the amount of compound B needed, denoted as \(compound\_B\), by multiplying \(total\_drug\) by \(ratio\_B\) and dividing by \(total\_ratio\). The result is 456.0.

Step 5 ：Final Answer: The chemist needs \(\boxed{456.0}\) milliliters of compound B to make 836 milliliters of the drug.