Final answer:
To find out how much of compound A a chemist needs to make 684 mL of a drug, given the ratio of compound A to B, calculate the number of sets of both compounds in 684 mL and then multiply by the amount of compound A per set, resulting in 304 mL of compound A.
Step-by-step explanation:
The student is asking how many milliliters of compound A are needed if a chemist wants to make 684 mL of a drug, given that there are 4 mL of compound A for every 5 mL of compound B. To solve this, we first need to find the total ratio of compounds A and B in the mixture (4 + 5 = 9 mL for both compounds).
We can then find out how many 9 mL sets are in 684 mL by dividing 684 by 9, which gives us 76 sets. Since each set contains 4 mL of compound A, we multiply the number of sets by 4 to get the total amount of compound A needed.
The calculation will be as follows:
Number of sets = 684 mL total volume / 9 mL per set = 76 sets
Compound A needed = 76 sets x 4 mL/set = 304 mL of Compound A
To find the amount of compound needed, we can set up a ratio using the information given. Since there are 4 mL of compound A for every 5 mL of compound B, the ratio of compound A to compound B is 4:5.
Let x represent the amount of compound B needed. Then, 4/5 = x/684. We can solve this proportion by cross multiplying and simplifying: 5x = 4 * 684, which gives x = (4 * 684) / 5.
Therefore, approximately 547.2 mL of compound B are needed to make 684 mL of the drug.