4.4 - Test Yourself!

Question 1

Which of these variables is not likely to follow a normal curve?

The number of cigarettes each student in your class smoked yesterday.
Correct. The number of cigarettes each student smoked. Since most students do not smoke at all, the number of cigarettes smoked would highly skewed right.
The weights of new rolls of quarters delivered to a bank (rolls have forty coins each).
The answer is the number of cigarettes each student smoked. Since most students do not smoke at all, the number of cigarettes smoked would highly skewed right.

Question 2

Which of these variables would be more likely to follow a normal curve?

The time to complete the course for all of the competitors in the Boston Marathon.
The answer is the difference between weights. The difference between like quantities will be symmetric while the marathon times will be highly skewed.
The difference between the weight today and the weight tomorrow of the cows at a large dairy farm.
Correct. The difference between weights. The difference between like quantities will be symmetric while the marathon times will be highly skewed.

Question 3

Which of these is true?

If a distribution is skewed to the left, then the median will typically have a negative standard score.

The answer is a standard score of zero. The median will have a positive standard score for left skewed and a negative standard score for right skewed. Since median = mean for symmetric distributions the standard score would be zero.
If a distribution is symmetric, then the median will have a standard score of zero.

Correct. A standard score of zero. The median will have a positive standard score for left skewed and a negative standard score for right skewed. Since median = mean for symmetric distributions the standard score would be zero.
If a distribution is skewed to the right, then the median will typically have a positive standard score.

The answer is a standard score of zero. The median will have a positive standard score for left skewed and a negative standard score for right skewed. Since median = mean for symmetric distributions the standard score would be zero.

Question 4

To see if the height of the father is positively associated with the height of the son you should make a:

bar graph
The answer is scatterplot. A scatterplot is used to visualize the association between two measurement variables.
line graph
The answer is scatterplot. A scatterplot is used to visualize the association between two measurement variables.
scatterplot
Correct. Scatterplot. A scatterplot is used to visualize the association between two measurement variables.

Question 5

To see if the value of gift purchases by American households is rising over the last fifty years, you would examine a:

time series plot of the amount of money spent on gifts.
The answer is a time series plot adjusted for inflation. Adjusting for inflation is important to make the amount spent more validly describe the value of the gift purchases.
a bar graph comparing the number of purchases in 1965 to the number in 2015.
The answer is a time series plot adjusted for inflation. Adjusting for inflation is important to make the amount spent more validly describe the value of the gift purchases.

Think About It! Section