Calculate the variance and the standard deviation of the data below 23. 19, 22, 30, 28

1 answer:

Alina [70]2 years ago

7 0

To get the variance, start with finding the mean of your data points:

(23 + 19 + 22 + 30 + 28) / 5 = 24.4

Now take each data point and subtract the mean from it, then square that value:

23 - 24.4 = -1.4 * -1.4 = 1.96

19 - 24.4 = -5.4 * -5.4 = 29.16

22 - 24.4 = -2.4 * -2.4 = 5.76

30 - 24.4 = 5.6 * 5.6 = 31.36

28 - 24.4 = 3.6 * 3.6 = 12.96

Now get the average of those new numbers. That is your variance:

(1.96 + 29.16 + 5.76 + 31.36 + 12.96) / 5 = 16.24

The standard deviation will be the square root of the variance:

√(16.24) = 4.0299 (rounded to 4DP)

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netineya [11]

Answer:

B. x = -1 ± i

General Formulas and Concepts:

Pre-Algebra

Order of Operations: BPEMDAS

Equality Properties

Algebra I

Algebra II

Step-by-step explanation:

Step 1: Define

x² + 2x = -2

Step 2: Identify Variables

Rewrite Quadratic in Standard Form [Addition Property of Equality]: x² + 2x + 2 = 0
Break up Quadratic: a = 1, b = 2, c = 2

Step 3: Solve for x

Substitute in variables [Quadratic Formula]: $\displaystyle x=\frac{-2 \pm \sqrt{2^2-4(1)(2)}}{2(1)}$
[√Radical] Evaluate exponents: $\displaystyle x=\frac{-2 \pm \sqrt{4-4(1)(2)}}{2(1)}$
Multiply: $\displaystyle x=\frac{-2 \pm \sqrt{4-8}}{2}$
[√Radical] Subtract: $\displaystyle x=\frac{-2 \pm \sqrt{-4}}{2}$
[√Radical] Factor: $\displaystyle x=\frac{-2 \pm \sqrt{-1}\sqrt{4}}{2}$
[√Radicals] Simplify: $\displaystyle x=\frac{-2 \pm 2i}{2}$
Factor: $\displaystyle x=\frac{2(-1 \pm i)}{2}$
Divide: $\displaystyle x = -1 \pm i$