Math 1040–1
(Practice) Midterm Exam #2
1. The length of horse pregnancies from conception to birth varies according to a roughly normal distribution with mean 336 days and standard
deviation 3 days.
(a) Find the percentage of horse pregnancies that take somewhere
between 330 and 340 days.
(b) What is the forty-ninth percentile of all horse pregnancies?
2. Compute the mean and the standard deviation of the data, 1, 2, 3, 4, 5.
You may use a calculator for the intervening steps, but must show all
of the computational work to earn credit.
3. Here are some summary statistics from across the world that you can
find in “The World Almanac and Book of Facts,” 1993:
• The correlation between life expectancy and the number of people
per T.V. set is −0.605;
• The average life expectancy was 67.76 years with a standard deviation of 7.8 years.
• The average number of people per T.V. was 51.97 people with a
standard deviation of 130.35 people.
(a) Find the equation of the regression line for the number of people per T.V. versus life expectancy. You must show all of the
calculations in order to earn any (partial or full) credit.
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(b) Use your calculation of the previous part to predict the life expectancy of a country where the average number of people per
T.V. is 1550.
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