Math 201 Practice Midterm I
Please work out each of the given problems.
Credit will be based on the steps
that you show towards the final answer.
Show your work.
Printable Key
Problem 1
Categorize these measurements associated with Lake Tahoe according to level:
nominal, ordinal, interval, or ratio.
A.
The depth of clarity of the lake.
B.
The time at which the first boat passes through from the Keys.
C.
The type of fish that is the first to be caught in the morning.
Solution
Problem 2
You are interested in finding out the average number of classes that students take at LTCC.
Since you can't find out this information for every student, you have all instructors who teach at
10:00 AM to survey all of their classes.
A. Is this a random sample? Explain your reasoning.
B. What type of sampling is this?
Solution
Problem 3
A. You did research to determine the number of snow boarders who rode Sierra each
Wednesday in January. You came up with the following data.
Week
1
2
3
4
No. of Boarders
800
600
400
900
Construct a time plot and a bar chart for this data.
Solution
Problem 4
You are interested in the distribution of tree size in the Lake Tahoe basin. You take a random
sample of 24 trees and measure their diameters (in inches). Below is the data that you
collected.
0 3 4 4 6 7 8 8 9 10 10 10 11 12 14
16 17 19 24 24 29 30 34 39
A. Make a frequency table and histogram for this data. Use 4 class intervals
Solution
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B. Make a Stem and Leaf Display of this data.
Solution
C. Describe the distribution of the data using the language of statistics.
Solution
D. If a 25th tree was found to have a diameter of
48
inches would the standard deviation
increase or decrease. (Answer this without calculating)
Solution
E. In what percentile is the tree that has a diameter of
7
inches?
Solution
Problem 5
Four students were asked to rate their statistics course on a scale of one to ten. The results were
3 3 8 10
Find the mean, median, mode, and standard deviation.
Solution
Problem 6
Who visits Lake Tahoe. Last weekend, 1000 people were observed entering the basin. Their age
distributions are given below.
Age
0  29
30  59
60  89
Number of Visitors
500
300
200
Estimate the mean and standard deviation for the age of the visitors.
Solution
Problem 7
Last year, 2,000,000 Kokanee Salmon hatched in Taylor Creek. Of those, only 20,000 reached
to one year. 12,000 of the survivors were female.
A. What is the estimated probability that a hatched egg will live for at least one year?
Solution
B. What is the estimated probability that a Kokanee that lives to one year will be female?
Solution
C. What is the estimated probability that a hatched egg will live for at least one year and will be
female?
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 Spring '10
 Driscoll
 Math, Statistics, Standard Deviation, Lake Tahoe, Lake Tahoe Basin

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