A prescription is written as 15 mL of antacid suspension, to be taken every 6 hours, each day. How many days will a 12 oz. bottle last?

3 days
6 days
10 days
15 days

6 days

Rationale: Since 15 mL is equivalent to 0.5 ounces, and "every 6 hours" means 4 times per day, this means that a total of 0.5 x 4 = 2 ounces of antacid must be taken each day. Therefore, a 12 ounce bottle, divided by 2 ounces per day, will last for 6 days.