Math Problem Statement

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Solve the hypothesis tests for calorie burning, customer satisfaction comparison, and persistence in learning based on the given data.

Solution

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Problem 1: Hypothesis test on calories burned by tennis players vs. basketball players

  • Given:
    • Mean calories burned by basketball players, μb=650\mu_b = 650
    • Sample mean calories burned by tennis players, xˉt=657\bar{x}_t = 657
    • Standard deviation of calories burned by tennis players, st=41.5s_t = 41.5
    • Sample size for tennis players, nt=37n_t = 37
    • Significance level: α=0.05\alpha = 0.05

Hypotheses:

  • Null Hypothesis (H0H_0): μt=μb\mu_t = \mu_b (mean calories burned by tennis players equals basketball players)
  • Alternative Hypothesis (HaH_a): μt>μb\mu_t > \mu_b (mean calories burned by tennis players is more than basketball players)

Test Statistic:

Since the sample size is 37 (greater than 30), we can use the Z-test: Z=xˉtμbstntZ = \frac{\bar{x}_t - \mu_b}{\frac{s_t}{\sqrt{n_t}}}

Critical Value:

For a one-tailed test at α=0.05\alpha = 0.05, the critical Z-value is approximately 1.645.

Decision Rule:

  • If Z>1.645Z > 1.645, reject H0H_0; otherwise, do not reject H0H_0.

Let me calculate the Z-value for you.

Problem 2: Comparing Customer Satisfaction Levels between Two Companies

  • Given:
    • n1=174n_1 = 174, n2=355n_2 = 355
    • xˉ1=3.51\bar{x}_1 = 3.51, xˉ2=3.24\bar{x}_2 = 3.24
    • s1=0.51s_1 = 0.51, s2=0.52s_2 = 0.52
    • Significance level: α=0.01\alpha = 0.01

Hypotheses:

  • Null Hypothesis (H0H_0): μ1=μ2\mu_1 = \mu_2 (mean satisfaction of Company 1 equals Company 2)
  • Alternative Hypothesis (HaH_a): μ1>μ2\mu_1 > \mu_2 (mean satisfaction of Company 1 is higher)

Test Statistic:

This is a two-sample Z-test for comparing means, and the test statistic is: Z=xˉ1xˉ2s12n1+s22n2Z = \frac{\bar{x}_1 - \bar{x}_2}{\sqrt{\frac{s_1^2}{n_1} + \frac{s_2^2}{n_2}}}

Critical Value:

For a one-tailed test at α=0.01\alpha = 0.01, the critical Z-value is approximately 2.33.

Decision Rule:

  • If Z>2.33Z > 2.33, reject H0H_0; otherwise, do not reject H0H_0.

Problem 3: Comparing Persistence in Learning between Boys and Girls

  • Given:
    • Girls: ng=14n_g = 14, xˉg=26.9\bar{x}_g = 26.9, sg=12s_g = 12
    • Boys: nb=11n_b = 11, xˉb=21.3\bar{x}_b = 21.3, sb=13s_b = 13
    • Significance level: α=0.01\alpha = 0.01

Part (a): Unequal variances (Welch’s t-test)

Hypotheses:

  • Null Hypothesis (H0H_0): μg=μb\mu_g = \mu_b (mean persistence for girls equals boys)
  • Alternative Hypothesis (HaH_a): μgμb\mu_g \neq \mu_b (mean persistence for girls is different)

Test Statistic:

For Welch’s t-test (unequal variances): t=xˉgxˉbsg2ng+sb2nbt = \frac{\bar{x}_g - \bar{x}_b}{\sqrt{\frac{s_g^2}{n_g} + \frac{s_b^2}{n_b}}}

Degrees of Freedom (df):

df=(sg2ng+sb2nb)2(sg2ng)2ng1+(sb2nb)2nb1df = \frac{\left(\frac{s_g^2}{n_g} + \frac{s_b^2}{n_b}\right)^2}{\frac{\left(\frac{s_g^2}{n_g}\right)^2}{n_g - 1} + \frac{\left(\frac{s_b^2}{n_b}\right)^2}{n_b - 1}}

Critical Value:

Use the t-distribution with the appropriate degrees of freedom and α=0.01\alpha = 0.01.

Part (b): Equal variances (pooled t-test)

Hypotheses:

  • Same as part (a).

Test Statistic:

For equal variances (pooled t-test): t=xˉgxˉbsp2(1ng+1nb)t = \frac{\bar{x}_g - \bar{x}_b}{\sqrt{s_p^2 \left(\frac{1}{n_g} + \frac{1}{n_b}\right)}} Where sp2s_p^2 is the pooled variance: sp2=(ng1)sg2+(nb1)sb2ng+nb2s_p^2 = \frac{(n_g - 1) s_g^2 + (n_b - 1) s_b^2}{n_g + n_b - 2}

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Math Problem Analysis

Mathematical Concepts

Hypothesis Testing
Z-Test
T-Test
Two-sample Comparison

Formulas

Z = (x̄ - μ) / (s / √n)
Z = (x̄1 - x̄2) / √((s1^2/n1) + (s2^2/n2))
T = (x̄1 - x̄2) / √(s_p^2 (1/n1 + 1/n2))
s_p^2 = [(n1-1)s1^2 + (n2-1)s2^2] / (n1+n2-2)

Theorems

Central Limit Theorem
Welch’s T-Test
Pooled T-Test
One-tailed and Two-tailed tests

Suitable Grade Level

Undergraduate Level (Statistics/Advanced Statistics)