A major airline company is concerned that its proportion of late arrivals has su

Question

A major airline company is concerned that its proportion of late arrivals has substantially increased in the past month. Historical data shows that on the average 18% of the company airplanes have arrived late. In a random sample of 1240 airplanes, 236 airplanes have arrived late. If we are conducting a hypothesis test of a single proportion to determine if the porportion of late arrivals has increased using the following hypotheses Ho: p <= .18 and Ha: > .18

What is thge value of the test statistic (4 dec.)

What is the p value (4 dec.)

What is the conclusion? (we should [reject or fail to reject] and conclude the proportion of late arrivals has [decreased or not changed or that no evidence exists to indicate the proportion of late arrivals is more than 18%])

Explanation / Answer

n= 1240 , x = 236

p = 0.18

Ho: p <= .18 and Ha: > .18

phat = 236/1240

phat = 0.19

z test = (phat - p) / sqrt(pq/n)

Z =(0.19/.018)/sqrt(0.18*0.82/1240)

Z = 0.9166

pvalue=0.1797 > alpha = 0.05

accept H0

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