Math Problem Statement

Pat ran an experiment to test the optimum power and time settings for microwave popcorn. His goal was to deliver popcorn with fewer than 10% of the kernels left unpopped, on average. He popped 8 bags of popcorn at a specific setting, and the percentages of unpopped kernels were recorded as follows: 2.2, 4.6, 2.7, 12.1, 12.6, 9.6, 13.7, and 3.8. Does this provide evidence that he met his goal of an average of fewer than 10% unpopped kernels? Use a 0.05 significance level.

Solution

This problem involves testing whether the average percentage of unpopped kernels is below 10%, based on the provided sample data. This is a one-sample t-test, as we have a sample of data and are comparing it to a known population mean (10%).

Steps to Solve

  1. Identify the Hypotheses:

    • Null hypothesis (H0H_0): The average percentage of unpopped kernels is 10% (or more). Mathematically, H0:μ10H_0: \mu \geq 10.
    • Alternative hypothesis (HaH_a): The average percentage of unpopped kernels is less than 10%. Mathematically, Ha:μ<10H_a: \mu < 10.
  2. Calculate the Test Statistic: The t-test statistic is given by: t=xˉμsnt = \frac{\bar{x} - \mu}{\frac{s}{\sqrt{n}}} where:

    • xˉ\bar{x} is the sample mean,
    • μ\mu is the population mean under H0H_0 (10% in this case),
    • ss is the sample standard deviation,
    • nn is the sample size.

    Given in the image:

    • Sample mean (xˉ\bar{x}) = 8.05 (assuming this from the t value),
    • Sample standard deviation (ss) = 3.42 (approx.),
    • n=8n = 8.
  3. Compute the p-value: The p-value represents the probability of observing a sample mean as extreme as, or more extreme than, the observed sample mean under the null hypothesis.

  4. Decision Rule:

    • If pp-value < 0.05, we reject H0H_0.
    • If pp-value ≥ 0.05, we fail to reject H0H_0.

Since the image already provides the tt-value as -1.37, we can proceed by finding the corresponding p-value for this t-statistic in a one-tailed test with n1=7n - 1 = 7 degrees of freedom.


Would you like further assistance on calculating the exact p-value or verifying the sample mean and standard deviation?

Here are some related questions to consider:

  1. What is the interpretation of a p-value in hypothesis testing?
  2. How do degrees of freedom impact the shape of the t-distribution?
  3. What conditions must be met to use a one-sample t-test?
  4. Why is a one-tailed test used in this scenario?
  5. What might be some sources of error in this experimental setup?

Tip: Always check the assumptions of your test, especially normality for small samples when using t-tests.

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Math Problem Analysis

Mathematical Concepts

Hypothesis Testing
One-Sample T-Test
P-Value Calculation

Formulas

t = (x̄ - μ) / (s / √n)

Theorems

T-Distribution

Suitable Grade Level

College Level