HVAC Math Practice Test 2026 – The Complete All-in-One Guide for Exam Success!

To determine the air quantity in cubic feet per minute (CFM) through a rectangular duct, we use the formula:

\[

\text{CFM} = \text{Area (sq. ft.)} \times \text{Velocity (FPM)}

\]

First, we calculate the area of the duct. Given the dimensions of the duct are 14 inches by 14 inches, we convert these measurements to feet. Since there are 12 inches in a foot, the dimensions in feet are:

\[

\text{Width} = \frac{14}{12} \text{ ft} = 1.167 \text{ ft}

\]

\[

\text{Height} = \frac{14}{12} \text{ ft} = 1.167 \text{ ft}

\]

The area of the duct is:

\[

\text{Area} = \text{Width} \times \text{Height} = 1.167 \text{ ft} \times 1.167 \text{ ft} \approx 1.36 \text{ sq. ft}

\]

Next, we can calculate the CFM by multiplying the area by the velocity:

\[

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