We want to know how many hours per week, on average, mothers
spend with their preschool...
We want to know how many hours per week, on average, mothers
spend with their preschool children. We draw a random sample of 300
mothers and find x bar=50.32 hours and s = 10.27 hours. What is the
interval within which, with 95% confidence, the true mean number of
hours a week all mothers spend with their preschool children falls?
Please interpret this confidence interval too.
13
We want to obtain a sample to estimate a population mean. Based
on previous evidence,...
13
We want to obtain a sample to estimate a population mean. Based
on previous evidence, researchers believe the population standard
deviation is approximately σ=67.9. We would like to be 99%
confident that the esimate is within 1 of the true population mean.
How large of a sample size is required?
n=
14
You want to obtain a sample to estimate how much parents spend
on their kids birthday parties. Based on previous study, you
believe the population standard deviation...
A consumer Organization want to develop a regression model to
predict gasoline mileage (as measured by...
A consumer Organization want to develop a regression model to
predict gasoline mileage (as measured by miles per gallon) based on
horsepower of the car's engine and the weight of the car, in
pounds. A sample of 50 percent recent car models was selected, with
the results recorded.
1. State the multiple regression equation.
2. Interpret the meaning of the slopes, b and b2 in this
problem.
3. Explain why the regression coefficient b0, has no practical
meaning in the...
QUESTION 3: As an avid golfer, you want to
estimate your average score for 18 holes...
QUESTION 3: As an avid golfer, you want to
estimate your average score for 18 holes of golf. Suppose you know
that the standard deviation of your score is 18.337 strokes and you
want to find a sample mean that is within 5.982 strokes of your
true average for all rounds of golf with 99% confidence. How many
rounds would you need to play to determine this?
QUESTION 4: In a climate survey, it was determined
that in a random...
An earlier exercise posed the following research question: "Many
cars have a recommended tire pressure of...
An earlier exercise posed the following research question: "Many
cars have a recommended tire pressure of 32 psi (pounds per square
inch). At a roadside vehicle safety checkpoint, officials plan to
randomly select 60 cars for which this is the recommended tire
pressure and measure the actual tire pressure in the front left
tire. They want to know whether drivers on average have too little
pressure in their tires." Suppose that the experiment is conducted,
and the mean and standard...
You want to know how the commuting time of your employees
compare to Departments competing for...
You want to know how the commuting time of your employees
compare to Departments competing for the same staff, so you get
some survey data on average commuting times for 25 randomly
selected people in your line of business.
Data: 59, 74, 73, 66, 80, 84, 90, 110, 37.2, 50, 101.8, 39, 80, 35,
88, 34, 82, 65, 61, 63, 66, 88, 70, 79, 75
You find that the mean commuting time is 70 minutes, with a
standard deviation of...