Math Problem Statement

Munchie's Potato Chip Company claims that the weight of the contents of a 10-ounce bag of chips is normally distributed, with mean 10 ounces. A consumer group, Snack Munchers for Truth (SMFT), says that the average weight is less than this: SMFT weighs the contents of 7 randomly selected bags of potato chips and gets the weights shown below. Test SMFT's claim. 10.1, 10, 9.7, 9.9, 9.7, 9.8, 9.7

Fill in the blank with the test value.

H_0:\mu=

What sign should appear in the alternative hypothesis? A. < B. > C. \neq

The test statistic for this test is .

The p-value for this test is .

Select the appropriate conclusion for this test at a significance level of \alpha=0.05. A. Reject H_0. We have significant evidence that the average weight is less than 10. B. Fail to reject H_0. We do not have significant evidence that the average weight is less than 10

Solution

To test SMFT's claim about the average weight of the chips, we can conduct a one-sample t-test. Here’s how we proceed:

  1. Formulating the Hypotheses:

    • Null Hypothesis (H0H_0): The true mean weight of the chips is 10 ounces.
      H0:μ=10H_0: \mu = 10
    • Alternative Hypothesis (HaH_a): The true mean weight of the chips is less than 10 ounces.
      • Answer to alternative hypothesis sign: A.<A. <
  2. Calculating the Sample Mean (xˉ\bar{x}) and Standard Deviation (s):

    Given weights: 10.1,10,9.7,9.9,9.7,9.8,9.710.1, 10, 9.7, 9.9, 9.7, 9.8, 9.7

    The sample mean is: xˉ=10.1+10+9.7+9.9+9.7+9.8+9.779.8414\bar{x} = \frac{10.1 + 10 + 9.7 + 9.9 + 9.7 + 9.8 + 9.7}{7} \approx 9.8414

    The sample standard deviation (ss) can be calculated as follows: s=(xixˉ)2n1s = \sqrt{\frac{\sum (x_i - \bar{x})^2}{n - 1}}

  3. Test Statistic Calculation:

    Using the formula for the t-test statistic: t=xˉμ0s/nt = \frac{\bar{x} - \mu_0}{s / \sqrt{n}} where μ0=10\mu_0 = 10 (the hypothesized mean), n=7n = 7 (sample size), and xˉ\bar{x} and ss are as calculated above.

  4. P-Value Calculation:

    With tt-value and degrees of freedom (df=n1=6df = n - 1 = 6), we find the p-value for a one-tailed test.

  5. Conclusion (Significance Level α=0.05\alpha = 0.05):

    If the p-value is less than 0.05, we reject H0H_0; otherwise, we fail to reject H0H_0.

Let's compute the exact values for the test statistic and p-value.The results are as follows:

  • Sample Mean (xˉ\bar{x}): 9.8429
  • Sample Standard Deviation (s): 0.1618
  • Test Statistic (t): -2.5690
  • P-Value: 0.0212

Conclusion at α=0.05\alpha = 0.05:

Since the p-value (0.0212) is less than the significance level of 0.05, we reject the null hypothesis H0H_0.

Final Answer:

  • Alternative Hypothesis Sign: A. <
  • Conclusion: A. Reject H0H_0. We have significant evidence that the average weight is less than 10 ounces.

Would you like more details or have any questions?

Related Questions:

  1. How would the test change if the significance level was set to 0.01?
  2. What if we had a larger sample size? How would it affect the test results?
  3. What are the assumptions of a one-sample t-test?
  4. How can we interpret the p-value in practical terms?
  5. What if we wanted to test if the average weight differs from 10 (two-tailed)?

Tip:

Remember, a smaller p-value indicates stronger evidence against the null hypothesis in hypothesis testing.

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Math Problem Analysis

Mathematical Concepts

Hypothesis Testing
One-Sample T-Test
Normal Distribution

Formulas

Sample mean \(\bar{x} = \frac{\sum x_i}{n}\)
Sample standard deviation \(s = \sqrt{\frac{\sum (x_i - \bar{x})^2}{n - 1}}\)
T-test statistic \(t = \frac{\bar{x} - \mu_0}{s / \sqrt{n}}\)

Theorems

Central Limit Theorem
Properties of the T-Distribution

Suitable Grade Level

College-level Statistics