Measurement Conversions: TEAS Practice Question with Answer & Explanation

Understanding Unit Conversions in Nursing Math

For the TEAS 7 exam, mastering multi-step unit conversions is essential. This question requires you to convert gallons to fluid ounces by navigating through an intermediate unit: cups. In clinical settings, you will frequently convert between different measurement systems (metric and household) to calculate fluid intake or medication dosages.

Multi-Step Solution

To find the total number of ounces in 1.5 gallons, follow these logical steps:

1. Convert Gallons to Cups: We are told that 1 gallon = 16 cups. Therefore, a 1.5-gallon container contains:

   • $1.5 \text{ gallons} \times 16 \text{ cups/gallon} = 24 \text{ cups}$

2. Convert Cups to Ounces: Next, use the conversion factor 1 cup = 8 fluid ounces.

   • $24 \text{ cups} \times 8 \text{ ounces/cup} = 192 \text{ ounces}$

Total: 192 ounces

Why the Other Choices are Incorrect

• Choice A (48 ounces): This result occurs if you multiply 1.5 (the gallons) by 16 (cups) but forget to then multiply by the 8 ounces per cup ($1.5 \times 16 \times 2$ or similar miscalculation). This represents just 6 cups.
• Choice B (96 ounces): This occurs if you only calculate the ounces in a single gallon ($1 \times 16 \times 8 = 128$) and then make a calculation error, or if you assume 1 gallon is only 8 cups ($1.5 \times 8 \times 8 = 96$).
• Choice D (384 ounces): This results from doubling the correct answer. It would be the amount in a 3-gallon container rather than a 1.5-gallon container.

Concept Summary: The "Bridge" Method

When you have multiple conversion factors, think of each factor as a bridge.

• Bridge 1: Gallon $\rightarrow$ Cup
• Bridge 2: Cup $\rightarrow$ Ounce

Memory Tip: Use the mnemonic "Big to Small, Multiply them All." When converting from a larger unit (gallons) to a smaller unit (ounces), you should always end up with a much larger number. If your final number is smaller than your starting number, you likely divided when you should have multiplied!