Before the hiring of an efficiency expert, the mean productivity of a firms employees was 45.4 units

Question:

Before the hiring of an efficiency expert, the mean productivity of a firm’s employees was 45.4 units per hour, with a standard deviation of 4.5 units per hour. After incorporating the changes recommended by the expert, it was found that a sample of 30 workers produced a mean of 47.5 units per hour. Using the 0.01 level of significance, can we conclude that the mean productivity has increased?