I need some help with a hypothesis test. The hypothesis is "You think that the mean systolic blood pressure is less than the national average of 124.7. Perform a hypothesis test at the 0.05 level of significance to verify this."

Here is the pertinent data: Sample size 300

Sample Mean: 122.96

Sample Standard Deviation, s: 15.85

This is what I got:

Z =122.96 - 124.7

15.85/300

Z = - 1.74

0.2298

Z = - 7.57

And using Statdisk I have a P value of 0.02910,

Also if the value is correct the null would not be supported and the alternate hypothesis would stand? I am a little unsure of this as well.

I am unsure if my Z score is accurate. I also need to show my work to get the P-value. If you can different answer or confirm mine please show your work either way.