Unit 1
The mean temperature in Glens Falls for the month of February is 23 degrees with a standard deviation of 4.2 degrees. What is the z-score for a temperature of 17 degrees?
-1.43
A linear regression model for the association between hours of sleep a student gets the night before an exam and their score on the exam generates an r Value of .71. What does this r Value tell us about the association between sleep and exam score?
There is a moderate positive association between sleep and exam score. Generally, more hours of sleep results in higher exam scores.
At a certain clothing store, the clothes are displayed on racks. The clothes on each rack have similar prices, but the prices among the racks are very different. To estimate the typical price of a single piece of clothing, a consumer will randomly select four pieces of clothing from each rack. What type of sample is the consumer selecting?
Stratified random sampling.
As a promotion, the first 50 customers who entered a certain store at a mall were asked to choose from one of two discounts. The first discount choice was 20% off all purchases made that day. The second discount choice was 10% off all purchases for the week. Of those who received the discounts, 28 chose the first discount and 22 chose the second discount. One customer will be selected at random from those who received a discount. Let F represent the event that the selected person chose the first discount, and let S represent the event that the selected person chose the second discount.
Are F and S mutually exclusive events?
Yes because P(F n S)=0
The shelf life of a particular dairy product is normally distributed with a mean of 12 days and a standard deviation of 3 days.
About what percent of the products last between 12 and 15 days?
34%
The height and collar size , both in centimeters, measured from a sample of boys were used to create the regression line c=-.94+0.9h. The line is used to predict collar size from height, both in centimeters, for boys’ shirt collars. Which value in the regression model has no meaning in the context of the problem?
The vertical intercept of -.94 for has no meaning because a real person can't have a height of 0 and a collar size of -.94 cm.
A randomized block design will be used in an experiment to compare two lotions that protect people from getting sunburned. What should be true about individuals within each block?
Individuals within each block should be as similar as possible in terms of how easily they get sunburned.
A fair die with its faces numbered from 1 to 6 will be rolled. What is the best interpretation of the probability that the number landing face up will be less than 3 ?
For many rolls of the die, the long-term relative frequency or rolling less than 3 is 1/3
The distribution of test scores for an AP Stats class is skewed left with a mean of 78. Describe/approximate the median of the distribution (no calculations necessary).
The median will be greater than 78.
Given a regression equation of y=12.3-.64x, calculate the residual of a point located at (8,7.9)
.72
A total of 13 distinct groups, but with each group similar to the other groups, participated in a craft fair. To investigate how satisfied the participants were with the fair, the fair director conducted a survey. The director randomly selected 5 of the groups participating in the fair and surveyed all members of the selected groups. What type of sampling method is used here?
Cluster sampling - all members of the 5 selected groups are used.
According to a recent survey, 81 percent of adults in a certain state have graduated from high school. If 15 adults from the state are selected at random, what is the probability that 5 of them have not graduated from high school?
.09
Use the 1.5 IQR rule to determine if there are any outliers for the following numbers:
84, 88, 72, 74, 98, 16, 94
16 is an outlier
A regression model has a negative slope. If an influential point (leverage point) located below the line close to the origin is removed, what with happen to the y-intercept of the regression line.
The y-intercept will increase.
A medical researcher conducted a study to investigate the effectiveness of two drugs, L and M, designed to reduce the number of seizures that people with epilepsy might have. Each person in a group of 120 adult volunteers who had epilepsy was randomly assigned to one of two groups. Those assigned to one group took drug L for one year, and those assigned to the other group took drug M for one year. Each participant recorded the number of seizures that occurred during the year.
To which group is it most reasonable to generalize the results of this study?
All adults with epilepsy that are similar to those who volunteered.
A certain computer chip company has a machine that makes a large number of computer chips. Of the computer chips produced on this machine, 3% are defective. Miriam, the quality control inspector, will randomly select computer chips from the machine to inspect.
What is the probability that the first defective computer chip Miriam finds is the sixth computer chip she inspects from the machine?
.0258
The 40 yards sprint times for a soccer team are found to be normally distributed with a mean of 5.2 seconds and a standard deviation of 0.3 seconds. What is the probability that a given runner takes longer than 5.6 seconds to complete the sprint?
.091
A regression model for the association between caffeine consumption and resting heart rate gives a coefficient of determination (r2 ) of .246. Interpret this value in context.
About 24.6% of increase in heart rate can be attributed to an increase in caffeine consumption.
Eighteen individuals who use a particular form of social media were assigned a new user interface to use when logging in to their accounts. After using the new user interface for a week, each individual was asked to rate how easy or hard the new user interface was to use on a scale from 1 (extremely easy) to 9 (extremely hard). Why this is not a well-designed experiment?
Only treatment is used -there is no control, so no comparative conclusion can be reached.
In 2014, 85 percent of households in the United States had a computer. For a randomly selected sample of 200 households in 2014, let the random variable C represent the number of households in the sample that had a computer. What are the mean and standard deviation of C ?
mean = 170 households
SD = 5.05