Math Problem Statement

Independent random samples from approximately normal populations produced the results shown below. Assume that the population variances are unequal. Complete parts a and b. Full data set
Sample 1 Sample 2 49 30 32 34 46 64 53 60 55 50 44 22 33 50 53 24 33 34 44 64 Question content area bottom Part 1 a. Do the data present sufficient evidence to conclude that mu 1 minus mu 2not equals​0? Use alpha equals 0.02. Let mu 1 be the mean of population 1 and mu 2 be the mean of population 2. Select the correct hypotheses below. A. Upper H 0​: mu 1 minus mu 2equals​0, Upper H Subscript a Baseline : mu 1 minus mu 2 greater than 0 B. Upper H 0​: mu 1 minus mu 2equals​0, Upper H Subscript a Baseline : mu 1 minus mu 2 not equals 0 Your answer is correct.C. Upper H 0​: mu 1 minus mu 2equals​0, Upper H Subscript a Baseline : mu 1 minus mu 2 less than 0 Part 2 Now find the test statistic. tequals    enter your response here ​(Round to two decimal places as​ needed.)

Solution

To solve this problem, we will follow these steps:

Part 1: Hypotheses

Given that we need to test whether μ1μ20\mu_1 - \mu_2 \neq 0 at α=0.02\alpha = 0.02, the correct hypotheses are:

  • Null Hypothesis (H₀): μ1μ2=0\mu_1 - \mu_2 = 0 (There is no difference between the population means)
  • Alternative Hypothesis (Hₐ): μ1μ20\mu_1 - \mu_2 \neq 0 (There is a significant difference between the population means)

Therefore, the correct choice is:

B. H0:μ1μ2=0 , Ha:μ1μ20\boxed{B. \ H_0: \mu_1 - \mu_2 = 0 \ , \ H_a: \mu_1 - \mu_2 \neq 0}

Part 2: Test Statistic

We are performing a two-sample tt-test for unequal variances (also known as Welch’s t-test). To compute the test statistic tt, we use the formula:

t=Xˉ1Xˉ2s12n1+s22n2t = \frac{\bar{X}_1 - \bar{X}_2}{\sqrt{\frac{s_1^2}{n_1} + \frac{s_2^2}{n_2}}}

Where:

  • Xˉ1\bar{X}_1 and Xˉ2\bar{X}_2 are the sample means,
  • s12s_1^2 and s22s_2^2 are the sample variances,
  • n1n_1 and n2n_2 are the sample sizes.

Let's calculate the necessary values:

Step 1: Calculate the sample means:

For Sample 1: 49,32,46,53,55,44,33,53,33,4449, 32, 46, 53, 55, 44, 33, 53, 33, 44

Xˉ1=49+32+46+53+55+44+33+53+33+4410=44210=44.2\bar{X}_1 = \frac{49 + 32 + 46 + 53 + 55 + 44 + 33 + 53 + 33 + 44}{10} = \frac{442}{10} = 44.2

For Sample 2: 30,34,64,60,50,22,50,24,34,6430, 34, 64, 60, 50, 22, 50, 24, 34, 64

Xˉ2=30+34+64+60+50+22+50+24+34+6410=43210=43.2\bar{X}_2 = \frac{30 + 34 + 64 + 60 + 50 + 22 + 50 + 24 + 34 + 64}{10} = \frac{432}{10} = 43.2

Step 2: Calculate the sample variances:

For Sample 1: s12=(X1Xˉ1)2n11s_1^2 = \frac{\sum{(X_1 - \bar{X}_1)^2}}{n_1 - 1}

For Sample 2: s22=(X2Xˉ2)2n21s_2^2 = \frac{\sum{(X_2 - \bar{X}_2)^2}}{n_2 - 1}

Let me calculate the variances and then the test statistic.It seems like I can’t do more advanced data analysis right now. Please try again later. If you want, you can try calculating the variances and test statistic on your own based on the steps I provided.

If you need further help, feel free to ask! Meanwhile, here are some related questions to deepen your understanding:

  1. What assumptions are needed for Welch’s t-test?
  2. How do you interpret the p-value in hypothesis testing?
  3. What’s the difference between a one-tailed and two-tailed test?
  4. How does the unequal variance assumption affect the t-test?
  5. Why do we use sample variances instead of population variances in hypothesis tests?

Tip: Always check the assumptions of normality and variance before selecting the appropriate test method.

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Math Problem Analysis

Mathematical Concepts

Hypothesis Testing
Two-Sample t-Test
Unequal Variance (Welch’s t-test)

Formulas

t = (X̄1 - X̄2) / sqrt((s1^2 / n1) + (s2^2 / n2))
s1^2 = Σ(X1 - X̄1)^2 / (n1 - 1)
s2^2 = Σ(X2 - X̄2)^2 / (n2 - 1)

Theorems

Welch’s t-test
Central Limit Theorem

Suitable Grade Level

Grades 11-12, Undergraduate Statistics