Question

Stemplots. In Exercises 7 and 8, construct the stem plot.

Diastolic Blood Pressure Refer to the data listed in Exercise 6. Identify the two values that are closest to the middle when the data are sorted in order from lowest to highest. (These values are often used to find the median, which is defined in Section 3-1.)

Short answer

The following stem plot is generated using the values of the blood pressure:

The two values that are closest to the middle are 72 mm Hg and 74 mm Hg.

Step-by-step solution

Given information

The data provided is on the female diastolic blood pressure (mm Hg).

Describe a stemplot

A stemplot is a graph that consists of stems and leaves expressed on the left and right sides of the vertical axis. The observations are split as stem and leaf according to the number of digits or decimals.

Sketch a stemplot

The steps to compute the stemplot:

• Arrange the data values in ascending order.
• Consider the digit at tens place of the pulse rate value as the stem and the one at the units place as the leaf.
• Draw a vertical line to separate the stem and leaves.
• Write the stems on the left side and the leaves on the right side.
• Note down the key of the stemplot.

The following stemplot is constructed:

Key: 8|2 represents 82 mm Hg diastolic blood pressure.

Note that the stemplot has values arranged from the smallest to the largest.

Determine the middle value

The middle value can be identified from the stemplot according to the total number of values present.

The total number of values is 24.

The two middle values correspond to the 12^th and 13^th values.

From the plot, it can be observed that the 12^th and the 13^th values are identified as 7|2 and 7|4, respectively.

Therefore, the two values closest to the middle of the data are equal to 72 mm Hg and 74 mm Hg.