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A diver records the depths, in feet, of her dives. They are:

[tex]\[ 60, 58, 53, 49, 60 \][/tex]

The mean of the data set is 56. Use the equation for variance below, along with the given data set, to answer the following questions.

[tex]\[
\sigma^2 = \frac{(x_1 - \mu)^2 + (x_2 - \mu)^2 + \ldots + (x_N - \mu)^2}{N}
\][/tex]

1. What does the numerator evaluate to? [tex]\[\quad\][/tex]
2. What does the denominator evaluate to? [tex]\[\quad\][/tex]
3. The variance equals: [tex]\[\quad\][/tex]


Sagot :

To solve for the variance of the given data set, we follow the steps below:

1. Collect the Data:
The depths of the dives are:
[tex]\[ 60, 58, 53, 49, 60 \][/tex]

2. Calculate the Mean:
The mean of the data set, [tex]\(\mu\)[/tex], is given as:
[tex]\[ \mu = 56 \][/tex]

3. Calculate the Numerator:
The numerator of the variance formula is calculated by summing the squared deviations of each data point from the mean:
[tex]\[ (60 - 56)^2 + (58 - 56)^2 + (53 - 56)^2 + (49 - 56)^2 + (60 - 56)^2 \][/tex]
Simplifying each term:
[tex]\[ (60 - 56)^2 = 4^2 = 16 \][/tex]
[tex]\[ (58 - 56)^2 = 2^2 = 4 \][/tex]
[tex]\[ (53 - 56)^2 = (-3)^2 = 9 \][/tex]
[tex]\[ (49 - 56)^2 = (-7)^2 = 49 \][/tex]
[tex]\[ (60 - 56)^2 = 4^2 = 16 \][/tex]
Summing these values:
[tex]\[ 16 + 4 + 9 + 49 + 16 = 94 \][/tex]
Therefore, the numerator evaluates to:
[tex]\[ 94 \][/tex]

4. Calculate the Denominator:
The denominator of the variance formula is the number of data points, [tex]\(N\)[/tex]. Given the data set:
[tex]\[ 60, 58, 53, 49, 60 \][/tex]
There are 5 data points, so:
[tex]\[ N = 5 \][/tex]
Therefore, the denominator evaluates to:
[tex]\[ 5 \][/tex]

5. Calculate the Variance:
The variance [tex]\(\sigma^2\)[/tex] is the numerator divided by the denominator:
[tex]\[ \sigma^2 = \frac{94}{5} = 18.8 \][/tex]
Therefore, the variance equals:
[tex]\[ 18.8 \][/tex]

To summarize:

- Numerator: [tex]\(94\)[/tex]
- Denominator: [tex]\(5\)[/tex]
- Variance: [tex]\(18.8\)[/tex]