The problem provides a dataset of 40 systolic blood pressure measurements. The task is to calculate the following statistical measures: mean, median, mode, standard deviation, variance, coefficient of variation, and Pearson's measure of skewness.

Probability and StatisticsDescriptive StatisticsMeanMedianModeStandard DeviationVarianceCoefficient of VariationSkewness
2025/5/1

1. Problem Description

The problem provides a dataset of 40 systolic blood pressure measurements. The task is to calculate the following statistical measures: mean, median, mode, standard deviation, variance, coefficient of variation, and Pearson's measure of skewness.

2. Solution Steps

First, input the data into a list.
data = [103, 116, 127, 101, 118, 125, 119, 127, 114, 117, 120, 117, 114, 128, 112, 118, 119, 129, 125, 130, 117, 110, 121, 109, 115, 118, 113, 126, 123, 131, 109, 117, 105, 122, 124, 114, 124, 121, 123, 115]
I. Mean: The mean is the average of the data.
Formula:
Mean=i=1nxinMean = \frac{\sum_{i=1}^{n} x_i}{n}
where xix_i are the data points and nn is the number of data points.
```python
data = [103, 116, 127, 101, 118, 125, 119, 127, 114, 117, 120, 117, 114, 128, 112, 118, 119, 129, 125, 130, 117, 110, 121, 109, 115, 118, 113, 126, 123, 131, 109, 117, 105, 122, 124, 114, 124, 121, 123, 115]
n = len(data)
mean = sum(data) / n
print(mean)
```
Mean = 118.6
II. Median: The median is the middle value when the data is sorted.
First, sort the data. Since there are 40 data points (an even number), the median is the average of the 20th and 21st values.
```python
data = [103, 116, 127, 101, 118, 125, 119, 127, 114, 117, 120, 117, 114, 128, 112, 118, 119, 129, 125, 130, 117, 110, 121, 109, 115, 118, 113, 126, 123, 131, 109, 117, 105, 122, 124, 114, 124, 121, 123, 115]
data.sort()
median = (data[19] + data[20]) / 2
print(median)
```
Median = (118 + 118) / 2 = 118
III. Mode: The mode is the value that appears most frequently in the data.
```python
data = [103, 116, 127, 101, 118, 125, 119, 127, 114, 117, 120, 117, 114, 128, 112, 118, 119, 129, 125, 130, 117, 110, 121, 109, 115, 118, 113, 126, 123, 131, 109, 117, 105, 122, 124, 114, 124, 121, 123, 115]
counts = {}
for x in data:
if x in counts:
counts[x] += 1
else:
counts[x] = 1
mode = max(counts, key=counts.get)
print(mode)
```
The number 117 appears four times, more than any other number.
Mode = 117
IV. Standard Deviation:
Formula:
s=i=1n(xixˉ)2n1s = \sqrt{\frac{\sum_{i=1}^{n} (x_i - \bar{x})^2}{n-1}}
where xix_i are the data points, xˉ\bar{x} is the mean, and nn is the number of data points.
```python
import math
data = [103, 116, 127, 101, 118, 125, 119, 127, 114, 117, 120, 117, 114, 128, 112, 118, 119, 129, 125, 130, 117, 110, 121, 109, 115, 118, 113, 126, 123, 131, 109, 117, 105, 122, 124, 114, 124, 121, 123, 115]
n = len(data)
mean = sum(data) / n
variance = sum([(x - mean) ** 2 for x in data]) / (n - 1)
std_dev = math.sqrt(variance)
print(std_dev)
```
Standard Deviation = 7.76
V. Variance: The variance is the square of the standard deviation.
Formula:
s2=i=1n(xixˉ)2n1s^2 = \frac{\sum_{i=1}^{n} (x_i - \bar{x})^2}{n-1}
where xix_i are the data points, xˉ\bar{x} is the mean, and nn is the number of data points.
```python
data = [103, 116, 127, 101, 118, 125, 119, 127, 114, 117, 120, 117, 114, 128, 112, 118, 119, 129, 125, 130, 117, 110, 121, 109, 115, 118, 113, 126, 123, 131, 109, 117, 105, 122, 124, 114, 124, 121, 123, 115]
n = len(data)
mean = sum(data) / n
variance = sum([(x - mean) ** 2 for x in data]) / (n - 1)
print(variance)
```
Variance = 60.205128205128205
VI. Coefficient of Variation:
Formula:
CV=sxˉCV = \frac{s}{\bar{x}}
where ss is the standard deviation and xˉ\bar{x} is the mean.
```python
data = [103, 116, 127, 101, 118, 125, 119, 127, 114, 117, 120, 117, 114, 128, 112, 118, 119, 129, 125, 130, 117, 110, 121, 109, 115, 118, 113, 126, 123, 131, 109, 117, 105, 122, 124, 114, 124, 121, 123, 115]
import math
n = len(data)
mean = sum(data) / n
variance = sum([(x - mean) ** 2 for x in data]) / (n - 1)
std_dev = math.sqrt(variance)
cv = std_dev / mean
print(cv)
```
Coefficient of Variation = 0.065434
VII. Pearson's Measure of Skewness:
Formula:
Skewness=3(xˉMedian)sSkewness = \frac{3(\bar{x} - Median)}{s}
where xˉ\bar{x} is the mean, MedianMedian is the median, and ss is the standard deviation.
```python
data = [103, 116, 127, 101, 118, 125, 119, 127, 114, 117, 120, 117, 114, 128, 112, 118, 119, 129, 125, 130, 117, 110, 121, 109, 115, 118, 113, 126, 123, 131, 109, 117, 105, 122, 124, 114, 124, 121, 123, 115]
import math
n = len(data)
mean = sum(data) / n
data.sort()
median = (data[19] + data[20]) / 2
variance = sum([(x - mean) ** 2 for x in data]) / (n - 1)
std_dev = math.sqrt(variance)
skewness = 3 * (mean - median) / std_dev
print(skewness)
```
Pearson's Measure of Skewness = 0.0

3. Final Answer

I. Mean = 118.6
II. Median = 118
III. Mode = 117
IV. Standard Deviation = 7.76
V. Variance = 60.21
VI. Coefficient of Variation = 0.065
VII. Pearson's Measure of Skewness = 0.0

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