+The amount of time required for an oil and filter change on an automobile is normally
distributed with a mean of 45 minutes and a standard deviation of 10 minutes. A
random sample of 16 cars is selected. What is the standard error of the mean?
TABLE 6-5
A company producing orange juice buys all of its oranges from a large orange orchard.
The amount of juice that can be squeezed from each of these oranges is approximately
normally distributed with a mean of 4.7 ounces and some unknown standard deviation.
The company’s production manager knows that the probability is 30.85% that a
randomly selected orange will contain less than 4.5 ounces of juice. Also, the
probability is 10.56% that a randomly selected orange will contain more than 5.2
ounces of juice. Answer the following questions without the help of a calculator,
statistical software or statistical table.
Referring to Table 6-5, what is the probability that a randomly selected orange will
contain between 4.5 and 5.2 ounces of juice?
TABLE 8-7
A hotel chain wants to estimate the mean number of rooms rented daily in a given
month. The population of rooms rented daily is assumed to be normally distributed for
each month with a standard deviation of 240 rooms. During February, a sample of 25
days has a sample mean of 370 rooms.
Referring to Table 8-7, a 99% confidence interval for the mean number of rooms rented
daily in a given month is from ________ to ________.
TABLE 17-8
The superintendent of a school district wanted to predict the percentage of students
passing a sixth-grade proficiency test. She obtained the data on percentage of students
passing the proficiency test (% Passing), daily mean of the percentage of students
attending class (% Attendance), mean teacher salary in dollars (Salaries), and
instructional spending per pupil in dollars (Spending) of 47 schools in the state.
Following is the multiple regression output with Y = % Passing as the dependent
variable, X1 = % Attendance, X2 = Salaries and X3 = Spending:
Referring to Table 17-8, estimate the mean percentage of students passing the
proficiency test for all the schools that have a daily mean of 95% of students attending
class, a mean teacher salary of 40,000 dollars, and an instructional spending per pupil of
2,000 dollars.
TABLE 12-16
As part of an evaluation program, a sporting goods retailer wanted to compare the
downhill coasting speeds of 4 brands of bicycles. She took 3 of each brand and
determined their maximum downhill speeds. The results are presented in miles per hour
in the table below.
Referring to Table 12-16, to use the chi-square critical value for the Kruskal-Wallis test,
the sample size in each group has to be greater than ________.
TABLE 3-7
In a recent academic year, many public universities in the United States raised tuition
and fees due to a decrease in state subsidies. The change in the cost of tuition, a shared
dormitory room, and the most popular meal plan from the previous academic year for a
sample of 10 public universities were as follows: $1,589, $593, $1,223, $869, $423,
$1,720, $708, $1,425, $922 and $308.
Referring to Table 3-7, what is the five-number summary of the change in the cost?
The amount of time necessary for assembly line workers to complete a product is a
normal variable with a mean of 15 minutes and a standard deviation of 2 minutes. The
probability is ________ that a product is assembled in between 15 and 21 minutes.