Find the P-value for the indicated hypothesis test.

In a sample of 88 children selected randomly from one town, it is found that 8 of them suffer from asthma. Find the P-value for a test of the claim that the proportion of all children in the town who suffer from asthma is equal to 11%.

A) 0.2843
B) 0.5686
C) 0.2157
D) –0.2843

1 answer

To find the P-value for the hypothesis test regarding the proportion of children suffering from asthma, we need to follow several steps:

  1. Define the Hypotheses:

    • Null hypothesis (\(H_0\)): \(p = 0.11\) (the proportion of children with asthma is equal to 11%)
    • Alternative hypothesis (\(H_a\)): \(p \neq 0.11\) (the proportion of children with asthma is not equal to 11%)
  2. Collect the Data:

    • Sample size (\(n\)) = 88
    • Number of children with asthma (\(X\)) = 8
    • Sample proportion (\(\hat{p}\)) = \(X/n = 8/88 = 0.0909\)
  3. Calculate the Test Statistic: The test statistic for a proportion is calculated using the formula:

    \[ z = \frac{\hat{p} - p_0}{\sqrt{\frac{p_0(1 - p_0)}{n}}} \]

    where \(p_0 = 0.11\) (the hypothesized population proportion).

    • \(\hat{p} = 0.0909\)
    • \(p_0 = 0.11\)
    • \(n = 88\)

    First, calculate the standard error (SE):

    \[ \text{SE} = \sqrt{\frac{p_0(1 - p_0)}{n}} = \sqrt{\frac{0.11(1 - 0.11)}{88}} = \sqrt{\frac{0.11 \times 0.89}{88}} \approx \sqrt{\frac{0.0979}{88}} \approx \sqrt{0.0011136} \approx 0.03334 \]

    Now, substituting into the z-formula:

    \[ z = \frac{0.0909 - 0.11}{0.03334} \approx \frac{-0.0191}{0.03334} \approx -0.571 \]

  4. Calculate the P-value: Since this is a two-tailed test, we will find the P-value for both tails of the normal distribution. We can find the P-value using the standard normal distribution (z-table) or a statistical calculator.

    The calculated \(z\) value is approximately \(-0.571\).

    Using a standard normal distribution calculator or table, find the P-value associated with \(z = -0.571\).

    • The area to the left of \(z = -0.571\) is approximately \(0.2843\).
    • Because it's a two-tailed test, we multiply this area by 2:

    \[ \text{P-value} = 2 \times 0.2843 \approx 0.5686 \]

  5. Conclusion: The P-value for the hypothesis test is 0.5686. Thus, the answer is:

B) 0.5686