# Create a 10x10 matrix of random numbers
# Find all numbers greater than 0.5
# Calculate their average
# Replace numbers less than 0.3 with 0

matrix = np.random.random((10, 10))
mask = matrix > 0.5
high_values = matrix[mask]
average = np.mean(high_values)
matrix[matrix < 0.3] = 0

print(f"Found {len(high_values)} values > 0.5")
print(f"Their average: {average:.3f}")