21. On Friday, the temperature at 8:00 a.m. was 49°F and rose at a constant rate of per hour until noon. A cold front passed through at noon, and the temperature then fell at a constant rate of 1°F per hour. The temperature first fell below 49°F between:

Answer and Explanation

Your Answer is

Correct Answer is C

Explanation

A total of 4 hours from eight o'clock to noon, so it rose to 51 degrees. It drops by 1 degree every hour, and it takes two hours to return to 49 degrees, which is two o'clock. If you need to continue to cool down below 49 degrees, choose C.