If $5 \mathrm{~mL}$ contains erythromycin ethylsuccinate $200 \mathrm{mg}$, then $2.4 \mathrm{~mL}$ contains how many $\mathrm{mg}$ of erythromycin ethylsuccinate?

Step 1 ：Given that 5 mL of a solution contains 200 mg of erythromycin ethylsuccinate, we are asked to find out how much erythromycin ethylsuccinate would be present in 2.4 mL of the same solution.

Step 2 ：This is a simple ratio problem. We can set up a ratio as follows: \(\frac{5 \text{ mL}}{200 \text{ mg}} = \frac{2.4 \text{ mL}}{x \text{ mg}}\).

Step 3 ：Solving for x, we get \(x = \frac{200 \text{ mg} \times 2.4 \text{ mL}}{5 \text{ mL}}\).

Step 4 ：Calculating the above expression, we find that \(x = 96.0 \text{ mg}\).

Step 5 ：Final Answer: The amount of erythromycin ethylsuccinate in 2.4 mL is \(\boxed{96.0 \text{ mg}}\).