a student recorded the ages of 4 zebras. The ages are 2, 9, 14, 15. The mean is 10....
Check the final answer first, then review the worked steps.
Check the final answer first, then review the worked steps.
1. Calculate the deviation of each age from the mean: The mean age is given as $\bar{x} = 10$ years. The deviations are calculated by subtracting the mean from each age.
- For age 2: $2 - 10 = -8$
- For age 9: $9 - 10 = -1$
- For age 14: $14 - 10 = 4$
- For age 15: $15 - 10 = 5$
2. Square each deviation: Squaring the deviations makes them all positive and emphasizes larger differences.
- $(-8)^2 = 64$
- $(-1)^2 = 1$
- $4^2 = 16$
- $5^2 = 25$
3. Sum the squared deviations: Add up all the squared deviations.
$64 + 1 + 16 + 25 = 106$
4. Calculate the variance: For a sample standard deviation, we divide the sum of squared deviations by $n-1$, where $n$ is the number of data points. Here, $n=4$.
Variance ($s^2$) = $\frac{\sum (x_i - \bar{x})^2}{n-1} = \frac{106}{4-1} = \frac{106}{3} \approx 35.3333$
5. Calculate the standard deviation: The standard deviation is the square root of the variance.
Standard Deviation ($s$) = $\sqrt{\text{Variance}} = \sqrt{\frac{106}{3}} \approx \sqrt{35.3333} \approx 5.9442$
6. Round the answer: Round the standard deviation to two decimal places as requested.
$5.9442 \approx 5.94$