Math Problems
MA 120 Practice Final Name: _________________________
1. Use the following sample data:
-1, 0, 1, 4, 6
a. (10 pts) Find the mean
b. (10 pts) Find the median
c. (10 pts) Find the mode
d. (10 pts) Find the standard deviation
2-3. Use the frequency distribution table below showing a sample data set for 10 students on a test
with a maximum score of 12 to find the mean score, �̅� and the standard deviation, s.
Score Frequency Midpoint Midpoint x Frequency
Midpoint squared x Frequency
1 – 3 2
4 - 6 4
7 – 9 3
10 - 12 1
Totals
2. (10 pts) �̅� =
3. (10 pts) s =
MA 120 Practice Final Name: _________________________
4. (10 pts) Acme Airlines flies airplanes that seat 10 passengers. From experience, they have learned
that, on average, 90% of the passengers holding reservations for a particular flight actually show up
for the flight. If they book 12 passengers for a flight, what is the probability that 10 or fewer
passengers holding reservations will actually show up for the flight?
5. (10 pts) Let X be a normally distributed random variable with μ = 10 and σ = 2. Find the probability that X is
between 7.5 and 11.
6. Using the table below showing the number of students who are taking a statistics course in the traditional
face-to-face mode versus online by gender. Assume one person is chosen at random from the 220. Enter your
answer as a fraction (a/b).
Online Traditional Totals
Male 30 60 90
Female 40 90 130
Totals 70 150 220
a. (10 pts) What is the probability that person is an traditional student and female?
b. (10 pts) What is the probability that person is a female student taking the course in the online mode?
MA 120 Practice Final Name: _________________________
7. (10 pts) If 10 letters addressed to 10 different zip codes are randomly ordered, what is the
probability they will end up in numerical order?.
1
10𝐶10
1
10𝑃10
10𝐶1
10𝑃1
8. (10 pts) What is the approximate minimum percentage of data in any frequency distribution that lies within 2
standard deviations of its mean?
75%
89%
99.7%
9. (10 pts) Suppose P(A|B) = P(A), P(A and B) = .32, and P(A) =.8. What is P(B)?
0.004
0.04
0.4
10. (10 pts) If A and B are mutually exclusive (disjoint) events which rule do we use?
P(A and B) = P(A) . P(B)
P(A or B) = P(A) + P(B)
11. (10 pts) Let a random sample be taken of size n = 50 from a normally distributed population with a known
standard deviation of σ = 2. Suppose that the mean of the sample is �̅� = 10. Find the 95% confidence interval
for the mean, μ, of the population from which the sample was drawn.