Hi there. Some help solving an econometrics task would be greatly appreciated. I don't get around very well in the field of econometrics and I most certainly don't know Excel functions.

So, the task is as follows.

A manufacturer of batteries has previouslyidentified that the average battery life is 299 hours. The producer is now interested in checking, whether the average battery life has expanded with technological advancements.

For that, 200 batteries were randomly chosen and tested. The average battery life was 300 hours with a standard deviation of 8 hours.The initial data, as I see it:

Control the hypethesis at a significance level of 5%.

H0:μ<=299H1:

μ>299

α= 0.05I'm correct so far, how do I proceed from here? Obviously it's a one-tailed test. But function do I use to determine the critical value? And how to find the upper confidence level?

X= 300

s= 8

Again, any help would be hugely appreciated.