# The mean of the Standard Normal Distribution

August 30, 2017

uestion
Math 243

Worksheet 9 – Review

Q 1: The mean of the Standard Normal Distribution is
Q 2: In a Normal distribution,

Summer 2015
.

percent of the data falls below the mean.

Q 3: Consider the following data: 30, 30, 33, 35, 37, 40, 40, 43, 45, 50. What is its ﬁve number summary?

Q 4: The amount of time (in minutes) that students at a particular school need to complete a standardized test
follows the N (40, 6) distribution.
a) If students are given 45 minutes to complete the exam, draw an appropriate picture (with shading) that
represents the amount (percent/proportion) of students expected to ﬁnish in the allotted time.

b) If students are given 45 minutes to complete the exam, what percent of students would be expected to
ﬁnish in the allotted time?

c) How much time would need to be allotted so that 90% of the students would be able to ﬁnish the exam.

1

Math 243

Worksheet 9 – Review

Summer 2015

Q 5: Suppose the scores on a particular test have a Normal distribution with mean 60 and standard deviation 15.
and

a) Approximately 68% of the scores fall between
b) Approximately

.

percent of the test-takers received a score of at least 75.

c) Bobby took the exam and received a score of 87. His score was
above the mean.

standard deviations

d) There are 36 students in the class, and we take a sample of 16 of them, of which 3 have blue eyes. What
is the probability that the average score of our sample is above 87?

Q 6: A simple random sample of size 5 is chosen from the 26 letters of the alphabet. Which of the following
statements are true?
a) It is impossible to randomly choose the letters A, B, C, D, E.
b) It is impossible to randomly choose the letters A, E, I, O, U.
c) It is possible to randomly choose the letters A, B, C, D, E but choosing the set R, D, K, E, J is more
likely.
d) Both (a) and (b) are true.
e) None of the above.
Q 7: Which of the following are valid probability distributions for a weighted 6-sided dice? (Select all that apply)
Outcome

A

B

C

D

1

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