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:
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Formulating the Hypotheses:
- Null Hypothesis (): The true mean weight of the chips is 10 ounces.
- Alternative Hypothesis (): The true mean weight of the chips is less than 10 ounces.
- Answer to alternative hypothesis sign:
- Null Hypothesis (): The true mean weight of the chips is 10 ounces.
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Calculating the Sample Mean () and Standard Deviation (s):
Given weights:
The sample mean is:
The sample standard deviation () can be calculated as follows:
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Test Statistic Calculation:
Using the formula for the t-test statistic: where (the hypothesized mean), (sample size), and and are as calculated above.
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P-Value Calculation:
With -value and degrees of freedom (), we find the p-value for a one-tailed test.
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Conclusion (Significance Level ):
If the p-value is less than 0.05, we reject ; otherwise, we fail to reject .
Let's compute the exact values for the test statistic and p-value.The results are as follows:
- Sample Mean (): 9.8429
- Sample Standard Deviation (s): 0.1618
- Test Statistic (t): -2.5690
- P-Value: 0.0212
Conclusion at :
Since the p-value (0.0212) is less than the significance level of 0.05, we reject the null hypothesis .
Final Answer:
- Alternative Hypothesis Sign: A. <
- Conclusion: A. Reject . We have significant evidence that the average weight is less than 10 ounces.
Would you like more details or have any questions?
Related Questions:
- How would the test change if the significance level was set to 0.01?
- What if we had a larger sample size? How would it affect the test results?
- What are the assumptions of a one-sample t-test?
- How can we interpret the p-value in practical terms?
- 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
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