To find the percent error, we can use the formula:
\[ \text{Percent Error} = \left| \frac{\text{Estimated Value} - \text{Actual Value}}{\text{Estimated Value}} \right| \times 100% \]
In this case, the estimated number of students is 40, and the actual number of students is 32.
Plugging in the values:
\[ \text{Percent Error} = \left| \frac{40 - 32}{40} \right| \times 100% \] \[ \text{Percent Error} = \left| \frac{8}{40} \right| \times 100% \] \[ \text{Percent Error} = 0.2 \times 100% \] \[ \text{Percent Error} = 20% \]
Since 20% is not among the options given, let's double-check if we need to interpret the term variably, and to clarify a further point of interest might be in mind. Assuming we seek the percent decrease instead could yield:
From 40 to 32, this decreases with: \[ \text{Percent Decrease} = \left| \frac{40-32}{40} \right| \times 100% = 20% \]
Hence valid alternative approaches remain non-matching. Thus concluding for absolute percent error is valid on needed pair matches without logical shift against misalignments in the problem’s range.
No applicable correct answer from the provided options accurately reflects the above percent error calculation of 20%. Please confirm or adjust provided options or statement interpretation.