Question

Six different​ second-year medical students at Bellevue Hospital measured the blood pressure of the same person. The systolic readings​ (in mmHg) are listed below. Find the​ range, variance, and standard deviation for the given sample data. If the​ subject's blood pressure remains constant and the medical students correctly apply the same measurement​ technique, what should be the value of the standard​ deviation?

Answer 1

Answer:

$Range=14$

$\sigma^2 =32.4$

$\sigma = 5 .7$

The standard deviation will remain unchanged.

Step-by-step explanation:

Given

$Data: 136, 129, 141, 139, 138, 127$

Solving (a): The range

This is calculated as:

$Range = Highest - Least$

Where:

$Highest = 141; Least = 127$

So:

$Range=141-127$

$Range=14$

Solving (b): The variance

First, we calculate the mean

$\bar x = \frac{1}{n} \sum x$

$\bar x = \frac{1}{6} (136+ 129+ 141+ 139+ 138+ 127)$

$\bar x = \frac{1}{6} *810$

$\bar x = 135$

The variance is calculated as:

$\sigma^2 =\frac{1}{n-1}\sum(x - \bar x)^2$

So, we have:

$\sigma^2 =\frac{1}{6-1}*[(136 - 135)^2 +(129 - 135)^2 +(141 - 135)^2 +(139 - 135)^2 +(138 - 135)^2 +(127 - 135)^2]$

$\sigma^2 =\frac{1}{5}*[162]$

$\sigma^2 =32.4$

Solving (c): The standard deviation

This is calculated as:

$\sigma = \sqrt {\sigma^2 }$

$\sigma = \sqrt {32.4}$

$\sigma = 5 .7$ --- approximately

Solving (d): With the stated condition, the standard deviation will remain unchanged.