91影视

The measurement of systolic blood pressure and diastolic blood pressure are given for 10 subjects in two samples.

The coefficient of variation measures theamount of variation present in a set of values interms of percentage. It is calculated using the given formula:

$C.V.=\frac{s}{\stackrel{炉}{x}}脳100$

Here,

$s$ is the sample standard deviation;

$\stackrel{炉}{x}$ is the sample mean.

Sample 1 shows the systolic blood pressures. The values of the sample mean are calculated as follows:

$$\begin{gathered} {\stackrel{炉}{x}}_1=\frac{\left(118+128+158+96+156+122+116+136+126+120\right)}{10} \\ =\frac{1276}{10} \\ =127.6 \end{gathered}$$

The sample standard deviation is calculated as follows:

$$\begin{gathered} s_1=\sqrt{\frac{{鈭�}_{i=1}^n{\left(x_i-{\stackrel{炉}{x}}_1\right)}^2}{n_1-1}} \\ =\sqrt{\frac{{鈭�}_{i=1}^{10}{\left(x_i-127.6\right)}^2}{10-1}} \\ =18.6 \end{gathered}$$

Thus, the sample mean is equal to 127.6 mm Hg, and the sample standard deviation is equal to 18.6 mm Hg.

The coefficient of variation for systolic blood pressure is as follows:

$$\begin{gathered} C{V}_1=\frac{s_1}{{\stackrel{炉}{x}}_1}脳100 \\ =\frac{18.6}{127.6}脳100 \\ =14.6\% \end{gathered}$$

Therefore, the coefficient of variation for systolic blood pressure is equal to 14.6%.

Sample 2 shows the diastolic blood pressures. The values of the sample mean is calculated as follows:

$$\begin{gathered} {\stackrel{炉}{x}}_2=\frac{\left(80+76+74+52+90+88+58+64+72+82\right)}{10} \\ =\frac{736}{10} \\ =73.6 \end{gathered}$$

The sample standard deviation is calculated as follows:

$$\begin{gathered} s_2=\sqrt{\frac{{鈭�}_{i=1}^n{\left(x_i-{\stackrel{炉}{x}}_2\right)}^2}{n_2-1}} \\ =\sqrt{\frac{{\left(80-73.6\right)}^2+{\left(76-73.6\right)}^2+...+{\left(82-73.6\right)}^2}{10-1}} \\ =12.5 \end{gathered}$$

Thus, the sample mean is equal to 73.6 mm Hg, and the sample standard deviation is equal to 12.5 mm Hg.

The coefficient of variation for diastolic blood pressure is calculated as follows:

$$\begin{gathered} C{V}_2=\frac{s_2}{{\stackrel{炉}{x}}_2}脳100 \\ =\frac{12.5}{73.6}脳100 \\ =16.9\% \end{gathered}$$

Therefore, the coefficient of variation for diastolic blood pressure is equal to 16.9%.

The coefficients of variation for the two samples are quite close.

Therefore, the variation in the two kinds of blood pressure measurements to the respective mean values is approximately the same.