An air traffic control error is said to occur when planes come too close to one another. The following data represent the number of air traffic control errors for a random sample of regions around the US for fiscal years 1996 and 2000.

a. Compute the sample mean number of errors in 1996 and 2000
b. Compute the median number of errors in 1996 and 2000.
c. Given the results of a. and b., decide whether the distrubution of "number of errors in 1996"
is symmetric, skewed right, or skewed left. What about number of errors in 2000?
d. Compute the sample standard deviation number of errors in 1996 and 2000. Which year is
more dispersed?
e. Compute the five number summary for each year.
f. On the same graph, draw boxplots for the two years. Add some general remarks comparing each year's errors.
g. Describe the shape of the distribution of each year, as shown in the boxplots. Does this confirm the result obtained in part c?
h. Determine whether the data for each year contain outliers.
i. Explain why comparing 1996 data to 2000 data maybe misleading.

18. Weights of males vs. females: According to the National Center for Health Statistics, the mean weight of a 20-29 female is 141.7 pounds,
with a standard deviation of 27.2 pounds. The mean weight of a 20-29 Male is 172.1 pounds, with a standard deviation of 36.5 pounds. Who is relatively
heavier: a 20-29 female who weighs 150 pounds or a 20-29 year old male who weighs 185 pounds? Why?

What is the Mean, Median, Mode and StandardDeviation using the following:
SAMPLE DATA: 2, 5, 7, 11, 12, 16, 16
1) What is the mean of X of the data above (TO THE NEAREST 1/10)?
2) What is the median of the data above?
3) What is the mode of the data above?
4) What is the standarddeviation of the data ab

For the data in the following sample:
8, 1, 5, 1, 5
A. Find the mean and the standarddeviation
B. Now change the score of x = 8 to X = 18, and find the new mean and standarddeviation.
C. Describe how one extreme score influences the mean and standarddeviation.

What are the characteristics of a standard normal distribution? Can two distributions with the same mean and different standard distributions be considered normal? How might you determine if a distribution is normal from its graphical representation?

The following data lists the average monthly snowfall for January in 15 cities around the US:
42 45 8 18 45 15 31 46
3 33 2 6 32 47 36
Find the mean, variance, and standarddeviation. Please show all of your work.

3-21
The following is a set of data for a population with N=10;
7 5 11 8 3 6 2 1 9 8
a. compute the population mean
b. compute the population standarddeviation
3-37
The following is a set of data from a sample of n=11 items
X 7 5 8 3 6 10 12 4 9 15 18
Y 21 15 24 9 18 30 36 12 27 45 54
a. Compute t

Use the empirical rule of statistics to explain the percentage of data values in a normal distribution that fall within:
a) 1 standarddeviation of the mean
b) 2 standarddeviations of the mean
c) 3 standarddeviations of the mean

The following sample was obtained from a population with unknown parameters. Scores: 6, 12, 0, 3, 4
a. Compute the sample mean and standarddeviation. (Note that these are descriptive values that summarize the sample data.)
b. Compute the estimated standard error for M. (Note that this is an inferential value that describe

Given the following frequency distribution, find the mean, variance, and standarddeviation. Please show all of your work.
Class Frequency
36-38 18
39-41 7
42-44 12
45-47 22
48-50 13

What does standarddeviation measure? In looking at the standarddeviations of the "with fireplace" and "without fireplace" selling prices, one is much larger than the other. What could cause the standarddeviations to be so different?