Question

Part 1: The Speed in miles per hour of SIX randomly selected
qualifiers for the Indiana 500 (in 2012) are listed below. Estimate
the mean qualifying speed with 99% confidence. Round your answers
to four decimal places.

223.422 223.684 224.037 225.172 226.240 226.484

Answer #1

Estimate 99% Confidence Interval,

i.e. Confidence level = 0.99, = 0.01

sample size (n) = 6

Degrees of Freedom = n-1 = 6-1 = 5

Critical value:

...............From t table.

Now , We find out 99% Confidence Interval:

(222.6604, 227.0193)

**We are 99% Confident that Population mean lies in that
Interval.**

Indy
500
Qualifier Speeds The speeds in miles per hour
of six randomly selected qualifiers for the Indianapolis
500 (in 2012) are listed below. Estimate the mean qualifying
speed with
90% confidence. Round your answers to at least four decimal
places.
223.422, 223.684, 224.037, 225.172, 226.240, 226.484

A construction zone on a highway has a posted speed limit of 40
miles per hour. The speeds of vehicles passing through this
construction zone are normally distributed with a mean of 45 miles
per hour and a standard deviation of 5.6 miles per hour. Find the
percentage of vehicles passing through this construction zone that
are exceeding the posted speed limit. Round to four decimal
places.

Samples of 100 8-hour shifts were randomly selected from the
police records for each of two districts in a large city. The
number of police emergency calls was recorded for each shift. The
sample statistics are listed below.
Region
1
2
Sample Size
100
100
Sample Mean
2.6
3.4
Sample Variance
1.24
2.54
Find a 90% confidence interval for the difference in the mean
numbers of police emergency calls per shift between the two
districts of the city. (Use μ1...

A truck driver travels at an average speed of 75 miles per hour
on a 210-mile trip to pick up a load of freight. On the return trip
(with the truck fully loaded), the average speed is 65 miles per
hour. What is the average speed for the round trip? (Round your
answer to one decimal place.)
answer: _________ mph

The manager of The Cheesecake Factory in Boston reports that on
six randomly selected weekdays, the number of customers served was
230, 235, 65, 185, 120, and 245. She believes that the number of
customers served on weekdays follows a normal distribution.
Construct the 99% confidence interval for the average number of
customers served on weekdays. (You may find it useful to
reference the t table. Round
intermediate calculations to at least 4 decimal places, "sample
mean" and "sample standard...

The speed of a car, measured in miles per hour, was determined
10 times at random. The results are 22, 43, 35, 32, 41, 28, 29, 30,
37, and 43 miles per hour. Construct a 95% confidence interval for
the mean speed of this vehicle. (4 points)
a. (28.9642, 39.0358)
b. (29.2226, 38.7774)
c. (28.9642, 38.7774)
d. (29.2226, 39.0358)
e. (29.9193, 38.0807)

The miles per gallon (mpg) for each of 20 medium-sized cars
selected from a production line during the month of March are
listed below. 23.2 21.4 23.7 23.8 20.3 24.5 25.4 27.1 24.8 22.8
26.3 23.3 26.0 24.8 24.5 24.3 25.0 22.3 23.0 24.7 (a) Find the
z-scores for the largest measurement. (Round your answers to two
decimal places.) (b) Find the z-scores for the smallest
measurement. (Round your answers to two decimal places.)

Traffic speed: The mean speed for a sample
of
36
cars at a certain intersection was
25.84
kilometers per hour with a standard deviation of
2.34
kilometers per hour, and the mean speed for a sample of
138
motorcycles was
38.85
kilometers per hour with a standard deviation of
3.84
kilometers per hour. Construct a
99
%
confidence interval for the difference between the mean speeds
of motorcycles and cars at this intersection. Let
μ1
denote the mean speed of...

A psychiatrist is interested in finding a 95% confidence
interval for the tics per hour exhibited by children with Tourette
syndrome. The data below show the tics in an observed hour for 11
randomly selected children with Tourette syndrome. Round answers to
3 decimal places where possible.
8
6
0
2
9
2
12
1
0
10
1
a. To compute the confidence interval use a
distribution.
b. With 95% confidence the population mean number of tics per
hour that...

A psychiatrist is interested in finding a 90% confidence
interval for the tics per hour exhibited by children with Tourette
syndrome. The data below show the tics in an observed hour for 11
randomly selected children with Tourette syndrome. Round answers to
3 decimal places where possible. 12 2 8 6 7 9 1 8 9 8 11
a. To compute the confidence interval use a distribution.
b. With 90% confidence the population mean number of tics per
hour that...

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