Question

In: Statistics and Probability

The mean arrival rate of flights at O'Hare Airport in marginal weather is 195 flights per...

The mean arrival rate of flights at O'Hare Airport in marginal weather is 195 flights per hour with a historical standard deviation of 17 flights. To increase arrivals, a new air traffic control procedure is implemented. In the next 30 days of marginal weather, the mean arrival rate is 201 flights per hour.

223 190 214 196 178 184 183 217 215 175
217 222 181 215 213 207 216 193 224 215
220 176 183 188 186 209 219 185 178 208
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(a)

Set up a right-tailed decision rule at α = .025 to decide whether there has been a significant increase in the mean number of arrivals per hour. Choose the appropriate hypothesis.

a. H1: μ > 195, reject H1 if z < 1.960
b. H1: μ < 195, reject H1 if z > 1.960
c. H0: μ ≥ 195, reject H0 if z < 1.960
d. H0: μ ≤ 195, reject H0 if z > 1.960
  • a

  • b

  • c

  • d

(b-1)

Calculate the test statistic. (Round your answer to 2 decimal places.)

  Test statistic   
(b-2) What is the conclusion?
  • There has not been a significant increase in the average number of flight departures.

  • There has been a significant increase in the average number of flight departures.

(b-3) Would the decision have been different if you used α = .01?
a.

No, z.01 = 2.33 and 1.93 < 2.33, so we would still have concluded that there is no evidence to indicate a significant increase.

b.

Yes, z.01 = 2.33 and 1.93 < 2.33, so we would still have concluded that there has been a significant increase in the average number of flight departures.

  • No

  • Yes

(c) What assumptions are you making, if any?
  • We have assumed that the type of distribution does not matter.

  • We have assumed a normal population or at least one that is not badly skewed.

  • We have assumed that the data follow a uniform distribution.

Solutions

Expert Solution

a)

d.H0: μ ≤ 195, reject H0 if z > 1.960

b-1)

test statistic z =1.93

b-2)

There has not been a significant increase in the average number of flight departures

No, z.01 = 2.33 and 1.93 < 2.33, so we would still have concluded that there is no evidence to indicate a significant increase.

We have assumed a normal population or at least one that is not badly


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