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Fiona recorded the number of miles she biked each day last week as shown below:

[tex]\[4, 7, 4, 10, 5\][/tex]

The mean is given by [tex]\(\mu = 6\)[/tex]. Which equation shows the variance for the number of miles Fiona biked last week?

A. [tex]\(s^2 = \frac{(4-6)^2 + (7-6)^2 + (4-6)^2 + (10-6)^2 + (5-6)^2}{6}\)[/tex]

B. [tex]\(\sigma^2 = \frac{(4-6)^2 + (7-6)^2 + (4-6)^2 + (10-6)^2 + (5-6)^2}{5}\)[/tex]

C. [tex]\(s = \sqrt{\frac{(4-6)^2 + (7-6)^2 + (4-6)^2 + (10-6)^2 + (5-6)^2}{4}}\)[/tex]

D. [tex]\(2(4-6)^2 + (7-6)^2 + (4-6)^2 + (10-6)^2 + (5-6)^2\)[/tex]

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Sagot :

To solve the problem, we need to determine the correct equation that shows the variance for the number of miles Fiona biked last week.

Given data:
Recorded miles: [tex]\(4, 7, 4, 10, 5\)[/tex]
Mean ([tex]\(\mu\)[/tex]): 6

The formula for the population variance ([tex]\(\sigma^2\)[/tex]) is:
[tex]\[ \sigma^2 = \frac{1}{N}\sum_{i=1}^{N} (x_i - \mu)^2 \][/tex]
where [tex]\(N\)[/tex] is the number of data points, [tex]\(x_i\)[/tex] represents each data point, and [tex]\(\mu\)[/tex] is the mean.

In this case:
1. Calculate the squared differences from the mean for each data point:
[tex]\[ (4-6)^2, (7-6)^2, (4-6)^2, (10-6)^2, (5-6)^2 \][/tex]
[tex]\[ 4, 1, 4, 16, 1 \][/tex]

2. Sum these squared differences:
[tex]\[ 4 + 1 + 4 + 16 + 1 = 26 \][/tex]

3. Divide by the number of data points ([tex]\(N = 5\)[/tex]) to get the variance ([tex]\(\sigma^2\)[/tex]):
[tex]\[ \sigma^2 = \frac{26}{5} = 5.2 \][/tex]

Given the choices, the only correct formula for the population variance [tex]\(\sigma^2\)[/tex] is:
[tex]\[ \sigma^2 = \frac{(4-6)^2 + (7-6)^2 + (4-6)^2 + (10-6)^2 + (5-6)^2}{5} \][/tex]

Therefore, the correct equation showing the variance for the number of miles Fiona biked last week is:
\[
\sigma^2 = \frac{(4-6)^2 + (7-6)^2 + (4-6)^2 + (10-6)^2 + (5-6)^2}{5}