1. Determine the level of measurement:
a) Voltage measurements from my house _____________________
b) Book genre _____________________
c) Outside temperature in Silver Spring _____________________
d) Restaurant ratings on a scale of 0-5 stars _____________________
2. Determine type of sampling used:
a) I collect data from this class _____________________
b) Data from every 4th patient in hospital _____________________
c) Data from 400 randomly selected students from those majoring in business, 763 randomly selected students from those majoring in education, and 392 randomly selected students from those majoring in criminal justice ¬_________________
d) Data from 4230 adults after their phone
numbers were randomly generated by computer ____________________
3. The frequency distribution below shows the distribution for checkout time (in minutes) in Trader Joe's grocery store between 8:00 and 9:00 AM on a Tuesday morning.
|
Checkout Time (in minutes)
|
Frequency
|
|
1.0 - 1.9
|
6
|
|
2.0 - 2.9
|
7
|
|
3.0 - 3.9
|
2
|
|
4.0 - 4.9
|
3
|
|
5.0 - 5.9
|
2
|
Using the data above, answer the following questions.
a. What percentage of the checkout times was at least 4 minutes?
b. Calculate the mean of this frequency distribution.
c. Calculate the standard deviation of this frequency distribution.
d. Assume that the smallest observation in this dataset is 1.2 minutes. Suppose this observation was incorrectly recorded as 0.12 instead of 1.2. What will happen to the mean and the median? Explain.
e. Create a histogram (not a bar graph!)
4. I counted the number of words on each posting from my Class Announcements and found the following:
128 130 133 137 138 142 142 144 147 149
151 151 151 155 156 161 163 163 166 172
What is the 5-number summary?
Construct a boxplot.
5. Environmental scientists measured CO2 emissions of a sample of cars in tons. Is the value of 9.3 unusual? Base your answers on the standard deviation, which must be included in your answer.
7.2 7.1 7.4 7.9 6.5 7.2 8.2 9.3
6. My cousin was 38 when she retired from the military. Most people who retire have a mean age of 43.8 years. The standard deviation is 8.9 years.
a) What is the difference between my cousin's age and the mean age?
b) How many standard deviations is that (difference found in part a)?
c) Convert my cousin's age to a z-score
d) If we consider "usual" age to be those that convert to a ¬z score between -2 and +2, is my cousin's age usual or unusual?