Answer:
D. +3.82
Explanation:
The null hypothesis is:
![H_(0) = 8500](https://img.qammunity.org/2021/formulas/mathematics/college/10g6463hc6f1qx5vzzy85zdgnyxlnxe7g5.png)
The alternate hypotesis is:
![H_(1) > 8500](https://img.qammunity.org/2021/formulas/mathematics/college/s0r5dyxrc6j03c2wn5eydhrlho8n1zpjw5.png)
Our test statistic is:
![t = (X - \mu)/((\sigma)/(√(n)))](https://img.qammunity.org/2021/formulas/mathematics/college/9llu6lnaocon8299nf5rvincsld9awwgww.png)
In which X is the sample mean,
is the expected mean(null hypothesis),
is the standard deviation of the population and n is the size of the sample.
In this problem:
![X = 8745, \mu = 8500, \sigma = 1200, n = 350](https://img.qammunity.org/2021/formulas/mathematics/college/scga172uh4o5u4r449ddlwznh680zcmumz.png)
So
![t = (X - \mu)/((\sigma)/(√(n)))](https://img.qammunity.org/2021/formulas/mathematics/college/9llu6lnaocon8299nf5rvincsld9awwgww.png)
![t = (8745 - 8500)/((1200)/(√(350)))](https://img.qammunity.org/2021/formulas/mathematics/college/ovj3h1jj5ipc4newv4i3f89fqfpycpqe9e.png)
![t = 3.82](https://img.qammunity.org/2021/formulas/mathematics/college/v7inpmsv2ef6azc4p7y4o3yp88wm1m3fbt.png)