Answer: 6
Explanation: To determine the frequency of the fifth class, We first need to know the class intervals and the range of the data. Once we have this information we can count the number of data points that fall within the fifth class interval.
The class intervals can be found by dividing the range of the data by the number of classes desired.
The range of the data is 1427 - 1071 = 356
If we use 5 classes, each class will have a width of 356/5=71.2.
The fifth class interval would be 1071+4*71.2=1216<X<=1287.2.
Now, We can count the number of data points that fall within this interval, the frequency of the fifth class is the number of data points that fall within the fifth class interval.
The data points that fall within the fifth class interval are: 1206, 1207, 1232, 1228, 1253, 1270
Frequency of the fifth class=6.