Answer: 3.5308
Step-by-step explanation:
Claim : The firm's professionals volunteer an average of more than 15 hours per month.
i.e. [tex]\mu>15[/tex]
Null hypothesis : [tex]H_0:\mu\leq15[/tex]
Alternative hypothesis : [tex]H_1:\mu>15[/tex]
Sample size : [tex]n=24[/tex]
The sample mean : [tex]\overline{x}=16.6\text{ hours}[/tex]
Sample standard deviation : [tex]\sigma=2.22\text{ hours}[/tex]
The test-statistics for the population mean is given by :-
[tex]z=\dfrac{\overline{x}-\mu}{\dfrac{\sigma}{\sqrt{n}}}[/tex]
i.e. [tex]z=\dfrac{16.6-15}{\dfrac{2.22}{\sqrt{24}}}=3.5307960256\approx3.5308[/tex]
Hence, the correct value of the test statistic for the appropriate hypothesis test is 3.5308.