North Seattle Community College
Winter 2011
ELEMENTARY STATISTICS
2617 MATH 109 - Section 05,
Chapter 3 and 4 – Test 2
STUDENT NAME: __________________________
6th February 2012
QUIZ SCORE: ______________________________
Question 1 (4 points)
a. Sara has a collection of 7 books: War and Peace, Steppenwolf, One Hundred
Years of Solitude, Huckleberry Finn, Lord of the Flies, The Old Man and the Sea,
The Grapes of Wrath.If she randomly selects three of her books to read in
sequence this month, what is the probability that she will read War and Peace,
Steppenwolf, and One Hundred Years of Solitude in that order?
b. If two-thirds of the books in the library are new, and half of the books in the
library are non-fiction, but only one-third of the new books are non-fiction, find
the probability that a book selected at random from the library is new, given that
it is a non-fiction book.
Question 2 (4 point)
You observe the gender of the next 100 babies born at a local hospital. You count the
number of female births. Assume that male and female births are equally likely.
a. What is the distribution of the number of female births?
b. What is the mean number of female births?
c. What is the standard deviation and variance of the number of female births?
Question 3 (7 points)
A shipment of 10 microwave ovens contains two defective units. A restaurant owner
buys three of these units.
a. What is the probability distribution of the number of defective units the
restaurant owner receives?
b. What is the mean and standard deviation of the number of defective units?
Question 4 (10 points)
In the Venn diagram below, event A represents the adults who drink coffee, event B
represents the adults who drink tea, and event C represents the adults who drink cola.
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Use the data in the diagram above to answer the following:
a. What is the probability that an adult drinks both coffee and tea?
b. What is the probability that an adult drinks only cola?
c. What is the probability that an adult does drinks none of the three?
d. Are A and B mutually exclusive? Explain why?
e. Are A and B independent? Explain why?