This problem is about statistics. From December 17 to
December 24, there are a total of 8 temperatures as data. However, one is
missing, so you only have 7. Since the average is known, we start from there:
By adding all the known data, the total is 37. Taking into
account the unknown, the sum is (37 + x). Thus,
(37 + x)/8 = 1.25
This results to x = -27. The low temperature on December 17
was -27.
