Final answer:
You will give approximately 4.17 milliliters of Tagamet liquid.
Step-by-step explanation:
To find the number of milliliters of Tagamet liquid to give, we can set up a proportion using the given information:
300mg/5ml = 250mg/x ml
Cross-multiplying and solving for x, we get:
x = (250mg * 5ml) / 300mg
= 4.17 ml
Therefore, you will need to give approximately 4.17 milliliters of Tagamet liquid.