National League for Nursing (NLN PAX) Practice Exam

To determine the correct amount of insecticide to add to half a gallon of water based on the specified dilution ratio, it’s important to first understand the initial ratio given in the question. The label states that for every gallon of water, 1 1/2 teaspoons of insecticide should be used.

Since half a gallon is being used, you can calculate the amount of insecticide needed by taking half of the specified amount for a full gallon.

1 1/2 teaspoons can be converted into an improper fraction which is 1.5 teaspoons. When you take half of that, you multiply 1.5 by 1/2. This gives:

1.5 teaspoons × 1/2 = 0.75 teaspoons.

Converting 0.75 teaspoons back into a fraction gives you 3/4 teaspoons. Therefore, for half a gallon of water, 3/4 teaspoons of insecticide should be added, making this the correct answer. This calculation ensures the pesticide is diluted appropriately, maintaining effective pest control while ensuring safety and efficacy.