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Organizing Data
Data Relationships
Producing Data & Experiments
Probability & Random Variables
Free Responses
100
This measure of center is more resistant to outliers than the mean.
What is the median?
100
observed y - predicted y
What is the residual?
100

A method of data collection that involves separating samples into different strata based on covariate characteristics.

What is stratified sampling?

100
This type of random variable requires a fixed number of trials.
What is a binomial random variable?
100

The average noise level in a bar is 36 decibels with a standard deviation of 5 decibels. Assuming a normal distribution, what is the probability the noise level is between 30 and 40 decibels?

.673

200
To calculate, subtract the mean of the distribution from the observed x, then divide by the standard deviation.
What is the z-score (or standardized value)?
200
Measures the direction and strength of a linear relationship between two quantitative variables.
What is correlation (or r)?
200

A general statistical term meaning a systematic favoring of certain outcomes.

What is bias?

200
The type of variable where the probability distribution assigns probability as the area under the density curve above a specific interval.
What is a continuous random variable?
200

During the 2006 NFL postseason play, the 12 participating teams scored the following numbers of passing touchdowns: {0,0,1,1,1,2,2,3,3,3,3,5} The trimean is defined as, Q1+ 2Med + (Q3)/4. Compute the trimean for the above data.

1+2(2)+3/4= 2.

300
This rule helps to determine if data is normally distributed by checking the number of observations within each interval.
What is the 68-95-99.7 rule?
300
The fraction of the variables in the values of y that is explained by the LSR of y on x.
What is the coefficient of determination (or r squared)?
300
This experimental design involves the random assignment of units to treatments which are carried out separately within each group of units known to be similar in some way that is expected to affect the responses.
What is block design?
300
Events that have no outcomes in common and can never occur simultaneously, for which the addition rule is used.
What are disjoint events (or mutually exclusive events)?
300

Suppose we calculate the melting points of eight metal rods and find the mean to be 1,400 degrees Fahrenheit with a standard deviation of 90 degrees Fahrenheit. What would be the mean and standard deviation of the melting points of the eight rods if the eight measurements were converted to Celsius?

The new mean is 760 degrees Celsius and the new standard deviation is 50 degrees Celsius. The size of the sample, n=8, is extraneous information.

400
The square of the standard deviation.
What is the variance?
400

If every man married a woman who was exactly 3 years younger than he, what would be the correlation between the ages of married men and women?

On the scatterplot, all the points would lie perfectly on a straight line sloping up to the right, so r=1.

400
The 3 basic principles of experimental design.
What are control, randomize, and replicate?
400

The conditions under which something can be considered a bernoulli trial.

Binary outcomes, Fixed probability, and the trials are independent. 

400

It turns out that 25 seniors at Fashionable High School took both the AP Statistics exam and the AP Spanish Language exam. The mean score on the Statistics exam for the 25 seniors was 2.4 with a standard deviation of 0.6 and the mean score on the Spanish Language exam was 2.65 with a standard deviation of 0.55. We want to combine the scores into a single score. What are the correct mean and standard deviation of the combined scores?

x-bar=5.05

S=sqrt(0.6^2+0.55^2)=.814

500

Using the most commonly accepted definition of outliers, a set has five outliers. If every value of the set is increased by 20 percent, how many outliers will there now be?

Using the most commonly accepted definition of outliers, a set has five outliers. If every value of the set is increased by 20 percent, how many outliers will there now be?

500

The linear model for a local store's Number of Sales people working versus Sales is as follows: Sales = 8,106 + 91.34(Number of Sales People Working). Does the y-intercept have meaning in this equation?

No, when no one is working, there should be no sales. This is just a starting point for the data.

500

In your results, this will be greatly reduced if you stratify the population properly.

What is variability?

500

It is known that about 90% of the widgets made by Buckley Industries meet specifications.  Every hour a sample of 18 widgets is selected at random for testing and the number of widgets that meet specifications is recorded.  What is the approximate mean and standard deviation of the number of widgets meeting specifciations.

Mean: 

μ x = (18)(.9)=16.2

Standard Deviation: 

sqrt(18(.9)(1-.9))=1.273

500

Suppose a police breathalyzer unit will correctly test positive for 98 percent of legally drunk drivers, but will also give a false positive reading for 3 percent of drivers whose actual blood alcohol concentration is under the limit. If 5 percent of late Saturday night drivers are legally drunk, and an officer arrests two drivers with positive readings, what is the probability that exactly one of the two is guilty of driving drunk?

P(drunk-pos test)=.049 P(sober-pos test)= .0285 P (pos test) = .0775 P(drunk|pos test)= .6323 P(sober| pos test)= .3677 P(exactly 1 success in 2 trials)= .4650