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The rectangular prism below is labeled with its measured dimensions. Taking measurement error into account, what is the percent error in its calculated volume?

5 in
16 in
4 in

Round your answer to the nearest tenth of a percent and include a percent sign (%).

1 answer

To calculate the percent error in the volume of the rectangular prism, we first need to determine the volume based on the given dimensions and then consider the measurement error.

Step 1: Calculate the nominal volume of the prism

The volume \( V \) of a rectangular prism is calculated using the formula:

\[ V = \text{length} \times \text{width} \times \text{height} \]

Using the given dimensions:

  • Length = 16 inches
  • Width = 5 inches
  • Height = 4 inches

Calculating the volume:

\[ V = 16 , \text{in} \times 5 , \text{in} \times 4 , \text{in} = 320 , \text{in}^3 \]

Step 2: Determine the measurement error

Assuming there is an error in the measurements of each dimension, let's establish a general way to evaluate this error. If we assume each measurement has a possible error of ±0.1 inches, we can find the maximum and minimum volumes.

Maximum Volume Calculation:

  1. Adjust each dimension by adding the error:

    • Length: \( 16 + 0.1 = 16.1 \)
    • Width: \( 5 + 0.1 = 5.1 \)
    • Height: \( 4 + 0.1 = 4.1 \)
  2. Calculate the maximum volume:

\[ V_{max} = 16.1 \times 5.1 \times 4.1 \] \[ V_{max} = 16.1 \times 5.1 = 82.11 , \text{in}^2 \] \[ V_{max} = 82.11 \times 4.1 \approx 337.651 , \text{in}^3 \]

Minimum Volume Calculation:

  1. Adjust each dimension by subtracting the error:

    • Length: \( 16 - 0.1 = 15.9 \)
    • Width: \( 5 - 0.1 = 4.9 \)
    • Height: \( 4 - 0.1 = 3.9 \)
  2. Calculate the minimum volume:

\[ V_{min} = 15.9 \times 4.9 \times 3.9 \] \[ V_{min} = 15.9 \times 4.9 = 78.11 , \text{in}^2 \] \[ V_{min} = 78.11 \times 3.9 \approx 304.23 , \text{in}^3 \]

Step 3: Calculate the percent error

With the maximum and minimum volumes calculated, we can find the percent error based on the nominal volume:

The error range can be expressed as follows:

  • In this case, we can calculate the absolute errors:
  1. Calculate the percent error for maximum volume: \[ \text{Percent Error}{max} = \left( \frac{|V{max} - V|}{V} \right) \times 100 \] \[ = \left( \frac{|337.651 - 320|}{320} \right) \times 100 \approx \left( \frac{17.651}{320} \right) \times 100 \approx 5.51% \]

  2. Calculate the percent error for minimum volume: \[ \text{Percent Error}{min} = \left( \frac{|V{min} - V|}{V} \right) \times 100 \] \[ = \left( \frac{|304.23 - 320|}{320} \right) \times 100 \approx \left( \frac{15.77}{320} \right) \times 100 \approx 4.93% \]

Summary

Now, taking the average of these two percent errors gives us an overall percent error in volume:

\[ \text{Average Percent Error} \approx \frac{5.51% + 4.93%}{2} \approx 5.22% \]

Final Answer

Rounding to the nearest tenth of a percent, the percent error in the calculated volume is:

\[ \boxed{5.2%} \]