Answer:
The mean salary increases by $50.
The standard deviation remains the same.
Explanation:
Since the mean salary is the average of all salaries, and every work recieved the same $50 raise, the mean salary increases by $50.
As for the standard deviation, it measures the dispersion of all values within a data set from the mean. Since the mean and each value on the set all increased by $50, the difference between them remains the same:
![x_i-M = (X_i+50)-(M+50)](https://img.qammunity.org/2021/formulas/mathematics/college/qtdv9f3jv71uswnbnsog0v6jldi4ctglue.png)
Therefore, the standard deviation remains the same.