## Q. 3.29

Systolic Blood Pressure

The frequency distribution for the systolic blood pressure readings (in millimeters of mercury, mm Hg) of 200 randomly selected college students is shown here. Construct a percentile graph.

 A Class boundaries B Frequency C Cumulative frequency D Cumulative percent 89.5–104.5 24 104.5–119.5 62 119.5–134.5 72 134.5–149.5 26 149.5–164.5 12 164.5–179.5 4 200

## Verified Solution

Step 1 Find the cumulative frequencies and place them in column C.
Step 2 Find the cumulative percentages and place them in column D. To do this step, use the formula

Cumulative % =$\frac{\text{cumulative frequency}}{n}$ · 100

For the first class,

Cumulative % =$\frac{24}{200}$ · 100 = 12%

The completed table is shown here.

Step 3 Graph the data, using class boundaries for the x axis and the percentages for the y axis, as shown in Figure 3–6.

 A Class boundaries B Frequency C Cumulative frequency D Cumulative percent 89.5–104.5 24 24 12 104.5–119.5 62 86 43 119.5–134.5 72 158 79 134.5–149.5 26 184 92 149.5–164.5 12 196 98 164.5–179.5 4 200 100 200