Math 221 Final Exam

MATH 221 Final Exam


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1. Explain the difference between a population and a sample. In
which of these is it important to distinguish between the two in order
to use the correct formula? mean; median; mode; range; quartiles;
variance; standard deviation.


2. The following numbers represent the weights in pounds of six 7-
year old children in Mrs. Jones' 2nd grade class.
{25, 60, 51, 47, 49, 45}
Find the mean; median; mode; range; quartiles; variance; standard
deviation.

3. If the variance is 846, what is the standard deviation?

4. If we have the following data
34, 38, 22, 21, 29, 37, 40, 41, 22, 20, 49, 47, 20, 31, 34, 66
Draw a stem and leaf. Discuss the shape of the distribution.


5. What type of relationship is shown by this scatter plot?


6. What values can r take in linear regression? Select 4 values in this
interval and describe how they would be interpreted.


7. Does correlation imply causation?

8. What do we call the r value.
9. To predict the annual rice yield in pounds we use the equation
yˆ = 859 + 5.76x1 + 3.82x2 , where x1 represents the number of acres
planted (in thousands) and where x2 represents the number of acres
harvested (in thousands) and where r2 = .94.

a) Predict the annual yield when 3200 acres are planted and 3000
are harvested.
b) Interpret the results of this r2 value.
c) What do we call the r2 value?
10. The Student Services office did a survey of 500 students in which
they asked if the student is part-time or full-time. Another question
asked whether the student was a transfer student. The results follow.

Transfer Non-Transfer Row Totals
Part-Time 100 110 210
Full-Time 170 120 290
Column Totals 270 230 500


a) If a student is selected at random (from this group of 500
students), find the probability that the student is a transfer student. P
(Transfer)
b) If a student is selected at random...