Use the given minimum and maximum data​ entries, and the number of​ classes, to find the ...

Givens:

minimum = 20 
maximum = 134​
classes = 8

My solution:

Class width = (max - min) / (# of classes) \(=\frac{134-20}{8}=\frac{57}{4}=14.25\)(round down to 14)

The first lower boundary is the minimum, 20. The rest are shown below:

min = 20
20 + 14 = 34
34 + 14 = 48
48 + 14 = 62
62 + 14 = 76
76 + 14 = 90
90 + 14 = 104
104 + 14 = 118
118 + 14 = 132
STOP, otherwise you go over the maximum

Now you need to find the upper boundaries. The upper boundaries are the lower boundaries PLUS the class width minus 1:

20 + 14 - 1 = 33
34 + 14 - 1 = 47
48 + 14 - 1 = 61
62 + 14 - 1 = 75
76 + 14 - 1 = 89
90 + 14 - 1 = 103
104 + 14 - 1 = 117
118 + 14 - 1 = 131
132 + 14 - 1 = 145

Therefore,

Class width is \(14\)
Lower limits are: \(20, 34, 48, 62, 76, 90, 104, 118, 132\)
Upper limits are: \(33, 47, 61, 75, 89, 103, 117, 131, 145\)