Statistics Midterm Exam Review | Baamboozle - Baamboozle

Identify a possible lurking variable for the relationship. It has been found that people living in larger cities tend to have higher rates of asthma.

Possible Answer: Air pollution

Which residuals plot indicates the data is appropriate for linear regression?

a

r = -0.62. What percentage of variation in number of hours of sleep is explained by the variation in the number of social media posts? Also, Is the correlation statistically significant or not?

r^2 = 38%, no the corelation is not significant since the Rcv for n = 8 is 0.707 and |-0.62| < |0.707|.

The line of best fit from the data in the table is: y = -0.404x + 8.821 and the correlation coefficient is r = -0.62. Use the regression equation to predict hours of sleep for a person who makes 9 social media posts. Are you extrapolating?

5.2 hours of sleep. Yes, this is extrapolation because 9 is outside the range of x-values used to create the regression equation.

Use the information provided in the graph to find the correlation coefficient (round to the nearest hundredth). Is the correlation positive or negative? Is the correlation strong or weak or is there no correlation?

r = - 0.93, negative, strong

What do statisticians use to measures both the strength and direction of a linear relationship. What letter is used to represent this measure?

The correlation coefficient, represented by the letter r.

Determine the probable explanatory variable and response variable in the following relationship: The number of hours a Marine infantryman sleeps the night before a field exercise and how alert they feel during the exercise.

Explanatory variable: Hours of sleep before the exercise. Response variable: Level of alertness during the exercise

Describe the graph in terms of its shape and direction. Also indicate if there are any outliers present.

Shape: linear, Direction: Positive, Outlier at around (2, 90).

Find the percentage of observations that have z-scores above z = -2.75. Round your answer to the nearest tenth of a percent.

99.7%

A runner completed a race in 37.5 minutes. The average time for this race is 48 minutes, with a standard deviation of 6 minutes. What is the runner’s z-score?

z = -1.75

State the mean and standard deviation of the normal curve shown. What is the official name of this normal curve?

The mean is 0 and the standard deviation is 1, Official name: The Standard Normal Curve

The weights of bags of flour are normally distributed, with a mean of 5 pounds and a standard deviation of 0.2 pounds. How heavy must a bag be to be in the heaviest 90% of all bags? Round to the nearest tenth of a pound.

4.7 lbs

Find the percentage of scores which are less than 3.5. Round your answer to the nearest tenth of a percent.

6.2%

Fill in the blanks: The Empirical Rule: About _____% of the data falls within ____ s.d. of the mean. About ____% of the data falls within ____ s.d. of the mean and about _____% of the data falls within ____ s.d. of the mean.

68%, ONE, 95%, TWO, 99.7% THREE

Using the normal curves shown, state the mean and the standard deviation for each distribution.

Blue distribution: mean is 75, standard deviation is 5. Red distribution: mean is 75, standard deviation is 10.

Fill in the blanks: If a set of data is skewed, then the ________________ will be pulled away from the ________________ in the direction of the _________________.

If a set of data is skewed, then the MEAN will be pulled away from the MEDIAN in the direction of the SKEW.

Multiple choice. From this box-plot, you can conclude that this data set is: a. Symmetric b. Skewed to the right c. Skewed to the left

b. Skewed to the left

The ages of a group of graduate students are distributed in the following box plot. Where does the lower 25% of the data lie? Where does the middle 50% of the data lie?

The lower 25% is from 24 to 27 years and the middle 50% is from 27 to 33 years.

The ages of a group of graduate students are distributed in the following box plot. Give the 5 Number Summary for the data from the box-plot.

L: 24, Q1: 27, M: 31, Q3: 33 , H: 34

Find the five-number summary with this set of data: 12, 13, 23, 25, 26, 26, 27, 30, 38, 39, 40

L: 12, Q1: 23, M: 26, Q3: 38, H: 40

Find the mean age of the following 7 people. Round to the nearest tenth: 17, 19, 35, 36, 39, 51, 61. How many of these people have ages below the mean?

36.9 years, 4 people have ages below the mean.

A split Stem-plot for a data set is shown. Write out the original data set used to create the split Stem-plot.

10, 13, 13, 14, 15, 25, 28, 28, 30, 31, 36

True or False? You ask several classmates how many credits they are taking. You have just collected quantitative data.

True

True or False? Histograms, stem-plots and line graphs display categorical data.

False