Exam Completion Time Distribution

import matplotlib.pyplot as plt
import numpy as np
from scipy import stats

np.random.seed(108)

times = np.random.normal(75, 20, 1000)
times = times[(times > 20) & (times < 120)]

kde = stats.gaussian_kde(times)
x = np.linspace(20, 120, 500)
y = kde(x)

fig, ax = plt.subplots(figsize=(12, 6), facecolor='#ffffff')
ax.set_facecolor('#ffffff')

ax.fill_between(x, y, alpha=0.4, color='#F527B0')
ax.plot(x, y, color='#F527B0', linewidth=3)

p25 = np.percentile(times, 25)
p75 = np.percentile(times, 75)
ax.axvspan(p25, p75, alpha=0.15, color='#27D3F5', label='Interquartile Range')
ax.axvline(90, color='#F5276C', linestyle='--', linewidth=2, label='Time Limit')

median = np.median(times)
ax.axvline(median, color='#374151', linestyle='-', linewidth=2)
ax.text(median+2, max(y)*0.9, 'Median: ' + str(int(median)) + ' min', color='#374151', fontsize=10, fontweight='bold')

ax.set_xlabel('Time (minutes)', fontsize=12, color='#1f2937', fontweight='500')
ax.set_ylabel('Density', fontsize=12, color='#1f2937', fontweight='500')
ax.set_title('Exam Completion Time Distribution', fontsize=16, color='#1f2937', fontweight='bold', pad=15)

ax.tick_params(colors='#374151', labelsize=10)
for spine in ax.spines.values():
    spine.set_color('#d1d5db')
ax.legend(loc='upper right', facecolor='#f9fafb', edgecolor='#d1d5db', labelcolor='#374151')
ax.grid(True, alpha=0.3, color='#e5e7eb')
ax.set_xlim(20, 120)

plt.tight_layout()
plt.show()