Sampling
When conducting a survey, which of the following is the most important reason to use a random sample?
To avoid bias and to get a representative sample
What percentage of students earned a grade of less than 70? Round your answer to the nearest whole number.
47%
Fill in the Blank:
Approximately __ of the observations fall within 1 standard deviation of
the mean.
Approximately __ of the observations fall within 2 standard deviations of
the mean.
Approximately __ (or virtually all) of the observations fall within 3
standard deviations of the mean.
Approximately 68% of the observations fall within 1 standard deviation of
the mean.
Approximately 95% of the observations fall within 2 standard deviations of
the mean.
Approximately 99.7% (or virtually all) of the observations fall within 3
standard deviations of the mean.
Is this Right Skewed or Left Skewed?
Left Skewed
True or False: The correlation r between two quantitative variables was found to be r = 0. This means there is no relationship between them
False.
In this case, which of the following is the population of interest?
All residents of the city
An urn contains 48 marbles consisting of 10 red marbles, 34 blue marbles, and 4 yellow marbles. What is the probability of randomly selecting a red marble from the urn?
Answer choices are rounded to the nearest whole percentage.
21%
The distribution of IQ (Intelligence Quotient) is approximately normal in shape with a mean of 100 and a standard deviation of 17.
According to the standard deviation rule, only __% of people have an IQ over 117.
16
Which Group has greater Variability in Scores?
Ms. Banana's Class
What is the relationship between the correlation r and the slope b of the least-squares line for the same set of data?
r and b have the same sign (+ or -)
What type of sampling is this?
Stratified Sampling
Suppose Joan has a fair four-sided die with sides that are numbered 1, 2, 3, and 4.
After she rolls it 33 times, Joan finds that she’s rolled the number 3 a total of four times. What is the empirical probability that Joan rolls a 3?
The distribution of the amount of money spent by students on textbooks in a semester is approximately normal in shape with a mean of 352 and a standard deviation of 22.
According to the standard deviation rule, approximately 95% of the students spent between what dollar amounts
308 and 396
An instructor asked her students how much time (to the nearest hour) they spent studying for the midterm. The data are displayed in the following histogram:
What do the numbers on the vertical axis represent?
The count of students falling in each of the intervals.
What would happen to the correlation coefficient (r) of this Scatterplot if the the Outlier was removed
What type of sampling is this?
Cluster
A family plans to have 3 children. For each birth, assume that the probability of a boy is the same as the probability of a girl. What is the probability that they will have at least one boy and at least one girl?
0.75
The outcomes are equally likely, so the easiest way to work this problem is to write out the 8 outcomes in this sample space. In two outcomes the gender of all three children is the same (GGG, BBB). The other 6 outcomes contain at least one boy and one girl.
The distribution of the amount of money spent by students on textbooks in a semester is approximately normal in shape with a mean of: μ= 390 and a standard deviation of: σ= 25.
According to the standard deviation rule, almost 16% of the students spent more than what amount of money on textbooks in a semester?
415
Dataset: 2, 5, 6, 7, 8, 9, 10, 14, 16, 17, 18, 19, 20, 21, 37
Is there an Outlier?
There are no outliers in this Dataset
Find the Slope (3 Decimals)
0.318
A survey was conducted to study the relationship between the annual income of a family and the amount of money the family spends on entertainment. Data were collected from a random sample of 280 families from a certain metropolitan area.
Which of the following would be a meaningful display of the data from this study?
Scatterplot
A scatterplot is the appropriate display of quantitative relationship (in other words, to display the relationship between a quantitative explanatory variable and a quantitative response variable).
A person must enter a 4 digit code to gain access to his cell phone. He will enter codes until he is successful, however he cannot try more than 3 times or the phone will lock him out. Let S denote a successful attempt and F denote a failed attempt. What is the sample space for this random experiment?
{S, FS, FFS, FFF}
The distribution of the amount of money spent by students for textbooks in a semester is approximately normal in shape with a mean of $235 and a standard deviation of $20. According to the standard deviation rule, how much money did approximately 99.7% of the students spend on textbooks in a semester?
Between $175 and $295
A couple decides to have three children. Let A define the event that the couple has at least 1 girl. What are the possible outcomes for this event? (G=girl, B=boy)
{GGG, GGB, GBG, BGG, GBB, BGB, BBG}
Find the y intercept (2 Decimals)
67.65