Z Score Calculation
1. The problem involves calculating the z-score for a list of values relative to a population and a sample.
2. First, let's define the dataset: $108, 200, 310, 150, 180, 119, 160, 180, 201, 190, 280, 202$.
3. We will calculate the mean ($\mu$ for population, $\bar{x}$ for sample) and the standard deviation ($\sigma$ for population, $s$ for sample).
4. Calculate the population mean:
$$\mu = \frac{108 + 200 + 310 + 150 + 180 + 119 + 160 + 180 + 201 + 190 + 280 + 202}{12} = \frac{2290}{12} = 190.83$$
5. Calculate the population variance:
$$\sigma^2 = \frac{\sum (x_i - \mu)^2}{N}$$
Compute each term:
$$(108-190.83)^2 = 6890.49, (200-190.83)^2 = 83.61, (310-190.83)^2 = 14001.49,$$
$$(150-190.83)^2 = 1670.49, (180-190.83)^2 = 117.36, (119-190.83)^2 = 5218.19,$$
$$(160-190.83)^2 = 951.19, (180-190.83)^2 = 117.36, (201-190.83)^2 = 104.89,$$
$$(190-190.83)^2 = 0.69, (280-190.83)^2 = 7913.89, (202-190.83)^2 = 124.69$$
Sum of squared differences = $42984.31$
$$\sigma^2 = \frac{42984.31}{12} = 3582.03$$
6. Calculate the population standard deviation:
$$\sigma = \sqrt{3582.03} = 59.85$$
7. For the sample calculations, mean $\bar{x} = 190.83$ (same as population mean as data is the full set) and sample variance:
$$s^2 = \frac{\sum (x_i - \bar{x})^2}{n-1} = \frac{42984.31}{11} = 3907.66$$
8. Sample standard deviation:
$$s = \sqrt{3907.66} = 62.53$$
9. Z-score formula for a value $x$ given population mean and standard deviation:
$$z = \frac{x - \mu}{\sigma}$$
10. Let's calculate the z-score for $x=200$ (for example):
$$z = \frac{200 - 190.83}{59.85} = \frac{9.17}{59.85} = 0.15$$
Final Answer:
Population mean $\mu = 190.83$
Population standard deviation $\sigma = 59.85$
Sample standard deviation $s = 62.53$
Example z-score for $x=200$ is approximately $0.15$.