The mean and standard deviation of \( 100 \) observations are \( 40 \) and \( 5.1 \), respectively. By mistake one observation is taken as \( 50 \) instead of \( 40 \). If the correct mean and the correct standard deviation are \( \mu \) and \( \sigma \) respectively, then \( 10(\mu + \sigma) \) is equal to:
