Last year in City X, the range of daily low temperatures, in degrees F

Last year in City X, the range of daily low temperatures, in degrees Fahrenheit, was 20 for the month of June and 25 for the month of July. Which of the following is the smallest possible range of City X's daily low temperatures, in degrees Fahrenheit, for the two-month period of June and July of last year?

A. 5

B. 20

C. 25

D. 30

E. 45

The range is the difference between the highest and lowest temperatures during the period in question.

Since the range for July is 25 and July is within the period in question, we know that, during the period in question, there were temperatures that differed by at least 25 degrees. So, the range for the two-month period cannot be less than 25.

So, we can eliminate choices (A) and (B).

Now, the question becomes whether the fact that June is also included in the period means that the range must be even greater than 25.

Since June's range is 20 degrees, it's possible that the June low was higher than the July low and that the June high was lower than the July high.

For example the July low and high could be 50 and 75, and the June low and high could be 52 and 72. In that case, the range would still be 25 since 25 is the difference between the highest and lowest temperatures for the entire period.

The correct answer is (C).