delivery_times = [10, 20, 30, 40, 50]  # minutes, Driver B

mean = sum(delivery_times) / len(delivery_times)

squared_diffs = []
for time in delivery_times:
    squared_diffs.append((time - mean) ** 2)

variance = sum(squared_diffs) / len(delivery_times)
std_dev = variance ** 0.5

print("Mean:", mean)
print("Variance:", variance)
print("Standard deviation:", round(std_dev, 2))
# Mean: 30.0
# Variance: 200.0
# Standard deviation: 14.14