The height (in inches) of the starting 5 players on the intramural basketball team is shown.

66, 70, 63, 75, 66

What is the five number summary of the data?

What is the standard deviation of the data?

Show your work.

(2 points)

1 answer

To calculate the five-number summary and the standard deviation of the heights of the starting 5 players (66, 70, 63, 75, 66), we can follow these steps.

Five-Number Summary

The five-number summary consists of the following:

  1. Minimum
  2. First Quartile (Q1)
  3. Median (Q2)
  4. Third Quartile (Q3)
  5. Maximum

Step 1: Sort the Data

First, we need to arrange the data in ascending order: \[ 63, 66, 66, 70, 75 \]

Step 2: Find the Minimum and Maximum

  • Minimum: 63
  • Maximum: 75

Step 3: Find the Median (Q2)

To find the median, we can look for the middle value. Since we have 5 values, the median is the 3rd value in the ordered list:

  • Median (Q2): 66

Step 4: Find Q1 and Q3

  • Q1: This is the median of the first half of the data (63, 66). So Q1 is the average of 63 and 66: \[ Q1 = \frac{63 + 66}{2} = \frac{129}{2} = 64.5 \]

  • Q3: This is the median of the second half of the data (66, 70, 75). Since there are three numbers, the Q3 is the second value:

    • Q3: 70

Five-Number Summary:

  • Minimum: 63
  • Q1: 64.5
  • Median (Q2): 66
  • Q3: 70
  • Maximum: 75

Standard Deviation

To find the standard deviation, we can use the following formula: \[ \sigma = \sqrt{\frac{\sum (x_i - \mu)^2}{n}} \]

Where:

  • \(x_i\) = each data point
  • \(\mu\) = mean of the data points
  • \(n\) = number of data points

Step 1: Calculate the Mean

\[ \mu = \frac{63 + 66 + 66 + 70 + 75}{5} = \frac{340}{5} = 68 \]

Step 2: Calculate the Squared Differences from the Mean

\[ \begin{align*} (63 - 68)^2 & = (-5)^2 = 25 \ (66 - 68)^2 & = (-2)^2 = 4 \ (66 - 68)^2 & = (-2)^2 = 4 \ (70 - 68)^2 & = (2)^2 = 4 \ (75 - 68)^2 & = (7)^2 = 49 \ \end{align*} \]

Step 3: Sum the Squared Differences

\[ \sum (x_i - \mu)^2 = 25 + 4 + 4 + 4 + 49 = 86 \]

Step 4: Calculate the Variance

\[ \sigma^2 = \frac{86}{5} = 17.2 \]

Step 5: Calculate the Standard Deviation

\[ \sigma = \sqrt{17.2} \approx 4.14 \]

Summary of Results

  • Five-Number Summary: \(63, 64.5, 66, 70, 75\)
  • Standard Deviation: Approximately \(4.14\) (rounded to two decimal places)