Answer:
Lower limit: 12 degrees Fahrenheit.
Upper limit: 20 degrees Fahrenheit
Step-by-step explanation:
The lower limit of the first class is always going to be the lowest value. The lowest temperature at 12 degrees Fahrenheit for a particular year. So the lower limit is going to be 12 degrees Fahrenheit.
To find the upper limit of the first class we have to first find the length of each class.
This is the highest temperature subtracted by the lowest, and divided by the number of classes.
91 - 12 = 79
10 classes
79/10 = 7.9 rounded up to 8.
So the upper limit will be 8 added to 12, 8+12 = 20.