Answer:
d. t distribution with df = 80
Step-by-step explanation:
Assuming this problem:
Consider independent simple random samples that are taken to test the difference between the means of two populations. The variances of the populations are unknown, but are assumed to be equal. The sample sizes of each population are n1 = 37 and n2 = 45. The appropriate distribution to use is the:
a. t distribution with df = 82.
b. t distribution with df = 81.
c. t distribution with df = 41.
d. t distribution with df = 80
Solution to the problem
When we have two independent samples from two normal distributions with equal variances we are assuming that
And the statistic is given by this formula:
Where t follows a t distribution with degrees of freedom and the pooled variance is given by this formula:
This last one is an unbiased estimator of the common variance
So on this case the degrees of freedom are given by:
And the best answer is:
d. t distribution with df = 80
Answer: D) Reflection across the y-axis; counterclockwise rotation about the origin
Answer:
x = 2/5
General Formulas and Concepts:
<u>Pre-Algebra</u>
Order of Operations: BPEMDAS
- Brackets
- Parenthesis
- Exponents
- Multiplication
- Division
- Addition
- Subtraction
Equality Properties
- Multiplication Property of Equality
- Division Property of Equality
- Addition Property of Equality
- Subtract Property of Equality
Step-by-step explanation:
<u>Step 1: Define</u>
5x = 2
<u>Step 2: Solve for </u><em><u>x</u></em>
- Divide 5 on both sides: x = 2/5
<u>Step 3: Check</u>
<em>Plug in x into the original equation to verify it's a solution.</em>
- Substitute in <em>x</em>: 5(2/5) = 2
- Multiply: 2 = 2
Here we see that 2 does indeed equal 2.
∴ x = 2/5 is the solution to the equation.
Answer:
200
Step-by-step explanation:
Use the ratio: 20/100 = 40/X
Simplify the ratio: 1/5 = 40/X
Cross Multiply: 1X = 200
Divide both sides by 1: 1X/1 = 200/1
Simplify: X = 200