Find the P-value for the indicated hypothesis test.

A nationwide study of American homeowners revealed that 65% have one or more lawn mowers. A lawn equipment manufacturer, located in Omaha, feels the estimate is too low for households in Omaha. Find the P-value for a test of the claim that the proportion with lawn mowers in Omaha is higher than 65%. Among 497 randomly selected homes in Omaha, 340 had one or more lawn mowers.

A) 0.1118
B) 0.0505
C) 0.0559
D) 0.0252

1 answer

To find the P-value for the hypothesis test, we can follow these steps:

  1. State the null and alternative hypotheses:

    • Null hypothesis (\(H_0\)): \(p = 0.65\) (the proportion of households with lawn mowers in Omaha is equal to 65%)
    • Alternative hypothesis (\(H_a\)): \(p > 0.65\) (the proportion of households with lawn mowers in Omaha is greater than 65%)
  2. Collect the sample data:

    • Sample size (\(n\)) = 497
    • Number of successes (households with lawn mowers) = 340
    • Sample proportion (\(\hat{p}\)) = \( \frac{340}{497} \approx 0.6847\)
  3. Calculate the standard error (SE):

    • Use the formula for the standard error of the proportion: \[ SE = \sqrt{\frac{p_0(1 - p_0)}{n}} \] where \(p_0 = 0.65\).

    \[ SE = \sqrt{\frac{0.65(1 - 0.65)}{497}} = \sqrt{\frac{0.65 \times 0.35}{497}} \approx \sqrt{\frac{0.2275}{497}} \approx \sqrt{0.000457} \approx 0.0214 \]

  4. Calculate the test statistic (Z): \[ Z = \frac{\hat{p} - p_0}{SE} \] \[ Z = \frac{0.6847 - 0.65}{0.0214} \approx \frac{0.0347}{0.0214} \approx 1.6203 \]

  5. Find the P-value: Since this is a one-tailed test (because \(H_a: p > 0.65\)), we will find the P-value associated with the calculated Z-value.

    Using a Z-table or a calculator, we can find:

    • The area to the right of \(Z = 1.6203\).

Using standard normal distribution, we find: \[ P(Z > 1.6203) \approx 0.0526 \]

Thus, the P-value is approximately 0.0526.

Looking at the options:

  • A) 0.1118
  • B) 0.0505
  • C) 0.0559
  • D) 0.0252

The closest option we can find that matches our approximate P-value is: C) 0.0559

This indicates that the P-value for this hypothesis test is most appropriately approximated by option C.