CH 8, 2, & 3
A classroom is broken into 4 groups of students and 2 students are selected from each group. What kind of sampling is this?
Stratified
Events are ________ when events A and B cannot occur at the same time.
disjoint
State whether the following is discrete or continuous:
The weight of an adult
continuous
A magazine said 81% of people gain weight in a relationship. In a random sample of 500 adults, 426 say this is true. What is the sample proportion of adults in relationships that have gained weight?
426/500=.852
How is a t interval different from a z interval?
standard deviation is unknown
How do you find the # of treatments?
Multiply levels of factors
What is the value of the correlation coefficient when r2 is .729?
r=+/-.8538
The distribution of heights for male teachers is normal, with mean 69 inches and a standard deviation of 1.8 inches.
Find the height where 15% of male teachers is shorter than that height.
697.134 inches
If the null hypotheses is false, but we fail to reject it what kind of error is made?
Type II error
In a local eating contest, the times are normally distributed with a mean of 11 minutes and a standard deviation of 2.1 minutes. A simple random sample of 15 contestants is taken.
Find the probability that the average for the sample of 15 contestants finishing times will be less than 8 minutes.
.0766=>7.66%
Name two proper graphs for categorical data
Bar chart & Pie chart
True or False:
If r=0 there is no relationship
False, if r=0 there is no linear relationship
X= Exam Scores, X~N(100, 10)
Use the Empirical Rule to find what percent of exam scores fell below 90.
16%
In order to decrease the ME for greater precision you can do two things...
decrease the CI or increase the sample size
An estimate is needed of the mean square feet of houses is LA. How large of a sample of stores is needed in order for a 95% confidence interval to have a ME of 21 square feet. Initial survey results indicate that the standard deviation is 61.
32.414=>33
Find the IQR using the listed data:
8, 10, 12, 13, 15, 18
15-10=5
Suppose P(A)=.40 and P(B)=.15, if P(A) and P(B) are independent what is P(A or B)?
P(A or B)=.4+.15-.06=.49
Suppose a student takes a quiz that has 5 multiple choice quiz with four options. Let X= # of questions answered correctly. Calculate P(X=0).
P(X=10)=(.75)5=.2373
In a random survey of 1000 students, 560 said they preferred savory over sweet. Construct a 95% confidence interval.
(.5292,.5908)
The stated amount of sugars in a Coca Cola can is 39 grams. In a random sample of Coca Cola cans the sample mean is 43, with a standard deviation of 9.1.
How many cans would be needed to estimate the average amount of sugars to within 7 grams with a 95% confidence interval?
6.76=>7
Kelly scored an 89% on her math exam. The class results for the math exam were normally distributed with a mean of 82% and a standard deviation of 4.5. Calculate the z-score.
89-82/4.5=1.56
There are 8 green marbles and 2 red marbles. Select 2 green marbles without replacement.
P(x=2)= 8/10*7/9=.6222
Assume that male teachers weights follow a normal curve with a mean of 235 pounds and a standard deviation of 10 pound.
Find the probability a male teacher, selected at random, is between 225 and 240 pounds?
P(225<X<240)=.5328
In 2010, 28% of college students dropped out of college. Test the claim that the dropout rate has raised if a random sample of 350 students results of 59 dropouts. Reject or Fail to Reject Ho.
Fail to reject Ho
A sample of 8 protein bars was selected, each tested to see how many calories contained. The following data was obtained:
50, 58, 62, 70, 75, 45, 75, 55
Calculate a 95% confidence interval for the mean amount of calories for all protein bars.
(51.794, 70.706)