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Unformatted text preview: NameSurname: Student ID: MIDDLE EAST TECHNICAL UNIVERSITY – NORTHERN CYPRUS
CAMPUS
SPRING 2011
BUS 152 Statistics for Social Sciences
Quiz 2 – Section 1
Questions and Solutions
1. There are five flights daily from Rome via Air Italia into Zurich. Suppose the
probability that any flight arrives late is 0.20. Assuming that the number of flights
arriving late is distributed as a binomial distribution, answer the following questions:
a.
b.
c.
d. What is the probability that exactly one of the flights is late in a day?
What is the probability that at most two of the flights are late in a day?
What is the probability that at least one of the flights is late in a day?
What are the mean and standard deviation of the number of flights arriving
late?
and . Let X be the number of flights arriving late. a. P(X = 1) = ?
( ) ( ( ) ( ) ) ( ( ) ) b. P(X ≤ 2) = ?
( )
( ( )
( ) ( ) ) ( ( ) = 0.94
c. ( )
( ) ( )(
d. Mean =
Standard deviation = (
) ) ( ) ,
√ ( ) 1 √( )( ) ) 2. A study of longdistance phone calls made from the corporate offices of XYZ
Company revealed that the length of the calls, in minutes, follows the normal
probability distribution. The mean length of time per call was 4.2 minutes and the
standard deviation was 0.6 minutes.
a. What is the probability that the calls made from the corporate offices of XYZ
Company last less than 5 minutes?
b. What is the probability that the calls made from the corporate offices of XYZ
Company last more than 4.5 minutes?
c. What is the probability that the calls made from the corporate offices of XYZ
Company last between 3 and 6 minutes?
d. The calls made from the corporate offices of XYZ Company last less than how
many minutes with 90% probability?
minutes and minutes Let X be the length of longdistance phone calls made from the corporate offices of
XYZ company b. ( ) ( a. ) ( ( ) )
( c. ) ( ( ) ( ) )
( )
( d. from Table E.2, p.813 ( (
) ( )
( ) )
( ) ( ) 0.90 corresponds to Z = 1.28 (from Table E.2, p.813)
( )( ) minutes 2 ) ...
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