Question

According to the U.S. Bureau of Transportation Statistics, 20% of airline flights in the United States failed to arrive on time in 2017. Airlines concentrated heavily to reduce this number for 2018. Suppose that in a recent random sample of 350 flights, 63 failed to arrive on time. Test at the 10% significance level whether the current percentage of all U.S. flights that fail to arrive on time decreased from 20%.C) Compute the Test Statistic D) Find the p-value (using a table in your book) E) Conclusion in terms of the problem

Answer 1

The hypothesis being tested is:

H₀: p = 0.20

H_a: p < 0.20

p̂ = 63/350 = 0.18

The test statistic, z = (p̂ - p)/√p(1-p)/n

z = (0.18 - 0.20)/√0.20(1-0.20)/350

z = -0.94

The p-value is 0.1748.

Since the p-value (0.1748) is greater than the significance level (0.10), we fail to reject the null hypothesis.

Therefore, we cannot conclude that the current percentage of all U.S. flights that fail to arrive on time decreased from 20%.

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