Finite Math Examples

Find the Standard Deviation table[[x,P(x)],[0,0/15],[1,1/15],[2,2/15],[3,3/15],[4,4/15],[5,5/15]]
Step 1
Prove that the given table satisfies the two properties needed for a probability distribution.
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Step 1.1
A discrete random variable takes a set of separate values (such as , , ...). Its probability distribution assigns a probability to each possible value . For each , the probability falls between and inclusive and the sum of the probabilities for all the possible values equals to .
1. For each , .
2. .
Step 1.2
is between and inclusive, which meets the first property of the probability distribution.
is between and inclusive
Step 1.3
is between and inclusive, which meets the first property of the probability distribution.
is between and inclusive
Step 1.4
is between and inclusive, which meets the first property of the probability distribution.
is between and inclusive
Step 1.5
is between and inclusive, which meets the first property of the probability distribution.
is between and inclusive
Step 1.6
is between and inclusive, which meets the first property of the probability distribution.
is between and inclusive
Step 1.7
is between and inclusive, which meets the first property of the probability distribution.
is between and inclusive
Step 1.8
For each , the probability falls between and inclusive, which meets the first property of the probability distribution.
for all x values
Step 1.9
Find the sum of the probabilities for all the possible values.
Step 1.10
The sum of the probabilities for all the possible values is .
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Step 1.10.1
Combine the numerators over the common denominator.
Step 1.10.2
Simplify the expression.
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Step 1.10.2.1
Add and .
Step 1.10.2.2
Add and .
Step 1.10.2.3
Add and .
Step 1.10.2.4
Add and .
Step 1.10.2.5
Divide by .
Step 1.11
For each , the probability of falls between and inclusive. In addition, the sum of the probabilities for all the possible equals , which means that the table satisfies the two properties of a probability distribution.
The table satisfies the two properties of a probability distribution:
Property 1: for all values
Property 2:
The table satisfies the two properties of a probability distribution:
Property 1: for all values
Property 2:
Step 2
The expectation mean of a distribution is the value expected if trials of the distribution could continue indefinitely. This is equal to each value multiplied by its discrete probability.
Step 3
Simplify each term.
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Step 3.1
Divide by .
Step 3.2
Multiply by .
Step 3.3
Multiply by .
Step 3.4
Multiply .
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Step 3.4.1
Combine and .
Step 3.4.2
Multiply by .
Step 3.5
Cancel the common factor of .
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Step 3.5.1
Factor out of .
Step 3.5.2
Cancel the common factor.
Step 3.5.3
Rewrite the expression.
Step 3.6
Multiply .
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Step 3.6.1
Combine and .
Step 3.6.2
Multiply by .
Step 3.7
Cancel the common factor of .
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Step 3.7.1
Factor out of .
Step 3.7.2
Cancel the common factor.
Step 3.7.3
Rewrite the expression.
Step 4
Combine fractions.
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Step 4.1
Combine the numerators over the common denominator.
Step 4.2
Simplify by adding numbers.
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Step 4.2.1
Add and .
Step 4.2.2
Add and .
Step 5
Find the common denominator.
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Step 5.1
Multiply by .
Step 5.2
Multiply by .
Step 5.3
Multiply by .
Step 5.4
Multiply by .
Step 5.5
Reorder the factors of .
Step 5.6
Multiply by .
Step 5.7
Multiply by .
Step 6
Combine the numerators over the common denominator.
Step 7
Simplify each term.
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Step 7.1
Multiply by .
Step 7.2
Multiply by .
Step 8
Reduce the expression by cancelling the common factors.
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Step 8.1
Add and .
Step 8.2
Add and .
Step 8.3
Cancel the common factor of and .
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Step 8.3.1
Factor out of .
Step 8.3.2
Cancel the common factors.
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Step 8.3.2.1
Factor out of .
Step 8.3.2.2
Cancel the common factor.
Step 8.3.2.3
Rewrite the expression.
Step 9
The standard deviation of a distribution is a measure of the dispersion and is equal to the square root of the variance.
Step 10
Fill in the known values.
Step 11
Simplify the expression.
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Step 11.1
Subtract from .
Step 11.2
Use the power rule to distribute the exponent.
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Step 11.2.1
Apply the product rule to .
Step 11.2.2
Apply the product rule to .
Step 11.3
Simplify the expression.
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Step 11.3.1
Raise to the power of .
Step 11.3.2
Multiply by .
Step 11.4
Combine.
Step 11.5
Cancel the common factor of and .
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Step 11.5.1
Factor out of .
Step 11.5.2
Cancel the common factors.
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Step 11.5.2.1
Factor out of .
Step 11.5.2.2
Cancel the common factor.
Step 11.5.2.3
Rewrite the expression.
Step 11.6
Simplify the expression.
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Step 11.6.1
Multiply by .
Step 11.6.2
Raise to the power of .
Step 11.6.3
Divide by .
Step 11.6.4
Write as a fraction with a common denominator.
Step 11.6.5
Combine the numerators over the common denominator.
Step 11.6.6
Subtract from .
Step 11.6.7
Move the negative in front of the fraction.
Step 11.7
Use the power rule to distribute the exponent.
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Step 11.7.1
Apply the product rule to .
Step 11.7.2
Apply the product rule to .
Step 11.8
Simplify the expression.
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Step 11.8.1
Raise to the power of .
Step 11.8.2
Multiply by .
Step 11.9
Combine.
Step 11.10
Simplify the expression.
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Step 11.10.1
Multiply by .
Step 11.10.2
Raise to the power of .
Step 11.10.3
Raise to the power of .
Step 11.10.4
Multiply by .
Step 11.11
To write as a fraction with a common denominator, multiply by .
Step 11.12
Combine and .
Step 11.13
Combine the numerators over the common denominator.
Step 11.14
Simplify the numerator.
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Step 11.14.1
Multiply by .
Step 11.14.2
Subtract from .
Step 11.15
Move the negative in front of the fraction.
Step 11.16
Use the power rule to distribute the exponent.
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Step 11.16.1
Apply the product rule to .
Step 11.16.2
Apply the product rule to .
Step 11.17
Simplify the expression.
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Step 11.17.1
Raise to the power of .
Step 11.17.2
Multiply by .
Step 11.18
Combine.
Step 11.19
Simplify the expression.
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Step 11.19.1
Raise to the power of .
Step 11.19.2
Raise to the power of .
Step 11.19.3
Multiply by .
Step 11.19.4
Multiply by .
Step 11.20
Cancel the common factor of and .
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Step 11.20.1
Factor out of .
Step 11.20.2
Cancel the common factors.
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Step 11.20.2.1
Factor out of .
Step 11.20.2.2
Cancel the common factor.
Step 11.20.2.3
Rewrite the expression.
Step 11.21
To write as a fraction with a common denominator, multiply by .
Step 11.22
Combine and .
Step 11.23
Combine the numerators over the common denominator.
Step 11.24
Simplify the numerator.
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Step 11.24.1
Multiply by .
Step 11.24.2
Subtract from .
Step 11.25
Move the negative in front of the fraction.
Step 11.26
Use the power rule to distribute the exponent.
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Step 11.26.1
Apply the product rule to .
Step 11.26.2
Apply the product rule to .
Step 11.27
Simplify the expression.
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Step 11.27.1
Raise to the power of .
Step 11.27.2
Multiply by .
Step 11.28
Combine.
Step 11.29
Cancel the common factor of and .
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Step 11.29.1
Factor out of .
Step 11.29.2
Cancel the common factors.
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Step 11.29.2.1
Factor out of .
Step 11.29.2.2
Cancel the common factor.
Step 11.29.2.3
Rewrite the expression.
Step 11.30
Simplify the expression.
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Step 11.30.1
Raise to the power of .
Step 11.30.2
Multiply by .
Step 11.31
To write as a fraction with a common denominator, multiply by .
Step 11.32
Combine and .
Step 11.33
Combine the numerators over the common denominator.
Step 11.34
Simplify the numerator.
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Step 11.34.1
Multiply by .
Step 11.34.2
Subtract from .
Step 11.35
Combine fractions.
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Step 11.35.1
Apply the product rule to .
Step 11.35.2
Combine.
Step 11.36
Simplify the numerator.
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Step 11.36.1
One to any power is one.
Step 11.36.2
Multiply by .
Step 11.37
Simplify the expression.
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Step 11.37.1
Raise to the power of .
Step 11.37.2
Multiply by .
Step 11.38
To write as a fraction with a common denominator, multiply by .
Step 11.39
Combine and .
Step 11.40
Combine the numerators over the common denominator.
Step 11.41
Simplify the numerator.
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Step 11.41.1
Multiply by .
Step 11.41.2
Subtract from .
Step 11.42
Apply the product rule to .
Step 11.43
Combine.
Step 11.44
Cancel the common factor of and .
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Step 11.44.1
Factor out of .
Step 11.44.2
Cancel the common factors.
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Step 11.44.2.1
Factor out of .
Step 11.44.2.2
Cancel the common factor.
Step 11.44.2.3
Rewrite the expression.
Step 11.45
Multiply by by adding the exponents.
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Step 11.45.1
Multiply by .
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Step 11.45.1.1
Raise to the power of .
Step 11.45.1.2
Use the power rule to combine exponents.
Step 11.45.2
Add and .
Step 11.46
Raise to the power of .
Step 11.47
Raise to the power of .
Step 11.48
Add and .
Step 11.49
To write as a fraction with a common denominator, multiply by .
Step 11.50
Write each expression with a common denominator of , by multiplying each by an appropriate factor of .
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Step 11.50.1
Multiply by .
Step 11.50.2
Multiply by .
Step 11.51
Combine the numerators over the common denominator.
Step 11.52
Simplify the numerator.
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Step 11.52.1
Multiply by .
Step 11.52.2
Add and .
Step 11.53
To write as a fraction with a common denominator, multiply by .
Step 11.54
Write each expression with a common denominator of , by multiplying each by an appropriate factor of .
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Step 11.54.1
Multiply by .
Step 11.54.2
Multiply by .
Step 11.55
Combine the numerators over the common denominator.
Step 11.56
Simplify the numerator.
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Step 11.56.1
Multiply by .
Step 11.56.2
Add and .
Step 11.57
Combine the numerators over the common denominator.
Step 11.58
Add and .
Step 11.59
To write as a fraction with a common denominator, multiply by .
Step 11.60
Write each expression with a common denominator of , by multiplying each by an appropriate factor of .
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Step 11.60.1
Multiply by .
Step 11.60.2
Multiply by .
Step 11.61
Combine the numerators over the common denominator.
Step 11.62
Simplify the numerator.
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Step 11.62.1
Multiply by .
Step 11.62.2
Add and .
Step 11.63
Cancel the common factor of and .
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Step 11.63.1
Factor out of .
Step 11.63.2
Cancel the common factors.
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Step 11.63.2.1
Factor out of .
Step 11.63.2.2
Cancel the common factor.
Step 11.63.2.3
Rewrite the expression.
Step 11.64
Rewrite as .
Step 11.65
Simplify the denominator.
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Step 11.65.1
Rewrite as .
Step 11.65.2
Pull terms out from under the radical, assuming positive real numbers.
Step 12
The result can be shown in multiple forms.
Exact Form:
Decimal Form: