need work shown if needed
1. Determine if the following variables are categorical or numeric. In addition, if they are numeric, whether
they are discrete or continuous.
Data Type Discrete/Continuous
a. The temperature (in degrees Celsius) at
which each piece of heat-resistant plastic
begins to melt _________________ _________________
b. The current unemployment rate (measured as
a percentage) for each of the 50 states _________________ _________________
c. The defective status (defective or not) of
computer chips manufactured by Intel _________________ _________________
d. The scores of law school applicants on the
LSATs. _________________ _________________
e. Cyanide concentration (parts per million)
of the rivers in Romania _________________ _________________
f. Weights (in grams) of the fish caught by a
deep-sea fishing party _________________ _________________
g. A taste-tester's ranking (best, worst, etc.) of
several brands of barbecue sauce _________________ _________________
h. Number of convicted murderers who receive the
death penalty each year _________________ _________________
i. The size of a car (subcompact, mid-size, or
full-size) rented by business travelers _________________ _________________
j. Number of census workers canvassing the city
for the 2000 federal census _________________ _________________
2. Thirty students in an experimental psychology class used various techniques to train a rat to move through a
maze. At the end of the course, each student's rat is timed through the maze. The mean time that it took the rats
to traverse the maze was 13.7 seconds with a standard deviation of 2.2 seconds. Using the 68 - 95-99.7 Rule,
determine the following:
a. What percentage of these rats made it through the maze in less than 9.3 seconds.
b. What percentage took longer than 15.9 seconds?
c. What is the probability that a particular rat took between 9.3 and 18.1 seconds?
d. What percentage of the rats took between 7.1 and 20.3 seconds?
e. What is the length time a particular rat took if only 2.5% of all times are shorter?
f. How many of the rats took less than 7.1 seconds or more than 20.3 seconds?
3. A manufacturer of computer work stations is investigating the down time of its systems. The 20 most recent
customers were surveyed to determine the amount of down time (in hours) they had experienced during the previous month. The data is listed below.
12 16 5 16 21 29 38 14 47 0
24 15 13 8 2 11 22 16 31 10
a. Construct an ordered stem-and-leaf plot for the data.
b. Find the mean length of down time, the median and the mode for the data.
c. Find the range, Q1 and Q3. What is the IQR for the data?
d. Determine the Five Number Summary.
4. A statistical analysis of 1,000 long distance telephone calls made from the headquarters of Johnson & Shurgot
Corporation indicates that the length of these calls is normally distributed with a mean of 240 seconds and a
standard deviation of 40 seconds.
e. What percentage of these calls lasted less than 180 seconds?
f. What percentage lasted longer than 300 seconds?
g. What is the probability that a particular call lasted between 180 and 280 seconds?
h. What percentage of the calls lasted between 110 and 180 seconds?
e. What is the length of a particular call if only 1% of all calls are shorter?
f. How many of the calls lasted less than 180 seconds or more than 300 seconds?
|Due By (Pacific Time)||02/16/2014 10:00 pm|
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