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Suppose a simple random sample of people played a game where each person tries to estimate the length of a minute without looking at a timer or clock. Their times (seconds) are below.

69, 39, 81, 65, 42, 21, 60, 63, 66, 48, 64, 70, 96, 91, 65.
Use a 0.05 significance level to test the claim that these are from a population with a mean equal to 60 seconds. Does it appear these people are reasonably good at estimating a minute?

1 Answer

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Final answer:

To determine if the sample estimates the length of a minute well, a hypothesis test using the t-distribution is performed with the null hypothesis being that the population mean is 60 seconds. The test involves calculating the t-statistic and comparing it to critical values at a 0.05 significance level.

Step-by-step explanation:

To test the claim whether the sample of people are reasonably good at estimating a minute (where the population mean is 60 seconds), we perform a hypothesis test.

Step-by-step process:

  1. State the null hypothesis (H0): The population mean is 60 seconds. (μ = 60).
  2. State the alternative hypothesis (Ha): The population mean is not 60 seconds. (μ ≠ 60).
  3. Calculate the sample mean (μ-bar) and the sample standard deviation (s).
  4. Determine the level of significance, which is given as 0.05.
  5. Since the sample size is less than 30, and we do not know the population standard deviation, we use the t-distribution.
  6. Calculate the t-statistic using the formula: t = (μ-bar - μ) / (s / √n), where n is the sample size.
  7. Find the critical t-value(s) for a two-tailed test with n - 1 degrees of freedom at the 0.05 significance level.
  8. Compare the calculated t-statistic to the critical t-value(s) to determine if we reject or fail to reject the null hypothesis.

If the t-statistic is within the range of the critical t-values, we fail to reject the null hypothesis, suggesting that the sample mean is not significantly different from 60 seconds. If the t-statistic falls outside this range, we reject the null hypothesis, indicating a significant difference.

By performing these steps, we can assess whether these people are reasonably good at estimating a minute.

User Kevin Nagurski
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