Sarah has gone four weeks. micah has been recording the daily high temperature. during that time, the high temperature has been greater than 45f on 20 out of 28 days. what is the experimental probability that the high temperature will be below 45f on the twenty-ninth day?

We have a total of 29 days from which 20 had higher temperature, so we are left with 9 days that could be higher or lower, 50% each possibility, so the total probability for the 29th day to be below 45F is 4.5 divided by 29, 4.5 because we have 50% chance of the 9 left days, so that is:
4.5/29 = 0.155
that is 15.5% that is the total experimental probability that the 29th day the temperature would be below 45F