The following data are the heights (in inches to the nearest half inch) of 100 male
semiprofessional soccer players. The heights are *continuous* data since height is measured.

• 60; • 60.5; • 61; • 61.5

• 63.5; • 63.5; • 63.5

• 64; • 64; • 64; • 64; • 64; • 64; • 64; • 64.5; • 64.5; • 64.5; • 64.5; • 64.5; • 64.5; • 64.5; • 64.5

• 66; • 66; • 66; • 66; • 66; • 66; • 66; • 66; • 66; • 66; • 66.5; • 66.5; • 66.5; • 66.5; • 66.5; • 66.5; • 66.5; • 66.5; • 66.5; • 66.5; • 66.5; • 67; • 67; • 67; • 67; • 67; • 67; • 67; • 67; • 67; • 67; • 67; • 67; • 67.5; • 67.5; • 67.5; • 67.5; • 67.5; • 67.5; • 67.5

• 68; • 68; • 69; • 69; • 69; • 69; • 69; • 69; • 69; • 69; • 69; • 69; • 69.5; • 69.5; • 69.5; • 69.5; • 69.5

• 70; • 70; • 70; • 70; • 70; • 70; • 70.5; • 70.5; • 70.5; • 71; • 71; • 71

• 72; • 72; • 72; • 72.5; • 72.5; • 73; • 73.5

• 74

The smallest data value is 60. Since the data with the most decimal places has one decimal (for instance, 61.5), we want our starting point to have two decimal places. Since the numbers 0.5, 0.05, 0.005, etc. are convenient numbers, use 0.05 and subtract it from 60, the smallest value, for the convenient starting point.

60 - 0.05 = 59.95 which is more precise than, say, 61.5 by one decimal place. The starting point is, then, 59.95.

The largest value is 74. 74+ 0.05 = 74.05 is the ending value.

Next, calculate the width of each bar or class interval. To calculate this width, subtract the starting point from the ending value and divide by the number of bars (you must choose the number of bars you desire). Suppose you choose 8 bars.

74.05−59.958=1.76
74.05
59.95
8
1.76

(2)We will round up to 2 and make each bar or class interval 2 units wide. Rounding up to 2 is one way to prevent a value from falling on a boundary. For this example, using 1.76 as the width would also work.

The boundaries are:

- 59.95
- 59.95 + 2 = 61.95
- 61.95 + 2 = 63.95
- 63.95 + 2 = 65.95
- 65.95 + 2 = 67.95
- 67.95 + 2 = 69.95
- 69.95 + 2 = 71.95
- 71.95 + 2 = 73.95
- 73.95 + 2 = 75.95

The heights 60 through 61.5 inches are in the interval 59.95 - 61.95. The heights that are 63.5 are in the interval 61.95 - 63.95. The heights that are 64 through 64.5 are in the interval 63.95 - 65.95. The heights 66 through 67.5 are in the interval 65.95 - 67.95. The heights 68 through 69.5 are in the interval 67.95 - 69.95. The heights 70 through 71 are in the interval 69.95 - 71.95. The heights 72 through 73.5 are in the interval 71.95 - 73.95. The height 74 is in the interval 73.95 - 75.95.

The following histogram displays the heights on the x-axis and relative frequency on the y-axis.