What descriptive statistical information is needed in order to determine if a current temperature of 75-degree is a departure from the average temperature of 65 for that date of the year in that particular location, if the record low is 35 and record high is 90 for that date?

Z = (score-mean)/SD

SD is estimated as 1/4 of range.

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability related to the Z score.