# Each day a commuter takes a bus to work, the transportation system has a phone app…

Each day a commuter takes a bus to work,

the transportation system has a phone app that tells her what

time the bus will arrive. She feels the app is often wrong,
either

making her late or missing the bus all together. For 6 weeks,

the rider randomly picks four times a week to measure if the

bus was off from the estimated arrival time at her stop to
work

(n =24). Each measurement is Actual Arrival Time App

Estimated Time. If the bus was early, she recorded the number

as a negative time difference. If the bus was on time, she

recorded it as a positive time difference. From her sample, the
average time difference of arrival versus the app is 0.77 minutes.
For ease she assumes the population is normal and the standard
deviation is ? = 2 ???????. If the bus app is consistently accurate
than the overall average should be close to zero.
State: Is there evidence that the average time between actual
arrival time and the bus app time is more than 0 minutes?
Plan:

(1 point) State the and alternative hypotheses to answer
the question of interest.

(2 points) Check conditions for inference. List the conditions
and state whether they are met.

Solve:
c. (2 points) Calculate the test statistic. Show work.

d. (1 point) What is the p-value for the test? Is it one or two
sided?
e. (3 points) Calculate a 90% confidence interval for
Conclude:
_. Show work. [1] 0.7720833
f. Write a four-part conclusion describing the results.

_ (1 point) Provide a statement in terms of the alternative
hypothesis.

_ (1 point) State whether the result is statistically
significant. That is, whether, or not, to reject the .

_ (1 point) State whether the result is practically significant
or not.

_ (1 point) Give an interpretation of the point and interval
estimate.

_ (1 point) Include context.