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
(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.