Answer: t=-5.651
Step-by-step explanation:
Let
be the population mean number of hours a week answering their email.
As per given we have
![H_0: \mu\geq7\\\\ H_a: \mu <7](https://img.qammunity.org/2020/formulas/social-studies/high-school/fmksvhxrgxx5lc93pw1tpwob3z4j0w1esa.png)
Sample size : n= 783
Sample mean :
![\overline{x}=5.54](https://img.qammunity.org/2020/formulas/social-studies/high-school/z1fcawz8ylexc9a2zjsx97j27ak0wplmy8.png)
Sample standard deviation: s=7.23
Since population standard deviation is unknown, so our test -statistic has a t-distribution.
Test statistic :
![t=\frac{\overline{x}-\mu}{(s)/(√(n))}](https://img.qammunity.org/2020/formulas/mathematics/college/o5f7ndax49gc4ekj7zics8ekqlldo8c792.png)
![=(5.54-7)/((7.23)/(√(783)))\\\\\\=(-1.46)/(0.2583791)\\\\\approx-5.651](https://img.qammunity.org/2020/formulas/social-studies/high-school/5nj8wmhfi869xlyi5f06ti6j3zn7u0r18x.png)
∴ The test statistic : t=-5.651