Answer:
(a)Mean: It increases by $23.
(b)Median: It stays the same.
Explanation:
The weekly salaries are given below:
![538,727,807,828,900,920,929](https://img.qammunity.org/2023/formulas/mathematics/college/amv2kbr67160ll0mcappb2w7g13vy0warp.png)
Part A
First, we find the mean of the initial salaries:
![Mean=(538+727+807+828+900+920+929)/(7)=(5649)/(7)=807](https://img.qammunity.org/2023/formulas/mathematics/college/587fkgmyv12m2hcgkdzjw9oszlmhwir8nr.png)
If the $538 salary changes to $699, then:
![Mean=(699+727+807+828+900+920+929)/(7)=(5810)/(7)=830](https://img.qammunity.org/2023/formulas/mathematics/college/1mnkvuzvrnlkdbuu1omnoitgxjd10ot2v9.png)
The difference = 830-807=23.
Therefore, if the $538 salary changes to $699, the mean increases by $23.
Part B
The median is the item in the middle of the data.
The initial weekly salaries are:
![\begin{gathered} 538,727,807,828,900,920,929 \\ \implies Median=828 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/ysq1hrtw0j40x4rysst10vbjab8vj74di4.png)
If the $538 salary changes to $699, the new weekly salaries are:
![\begin{gathered} 699,727,807,828,900,920,929 \\ \implies Median=828 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/oca3iw30asm4bmat3qxphw75lj3ey1h7md.png)
The median stays the same.