MAS 291 EXAM REVISION QUESTIONS AND
100% CORRECT ANSWERS!!
A study of 1000 randomly selected flights of a major airline showed that 782 of the flights
arrived on time. What is the probability of a flight arriving on time?
a. 391/500
Assume that the weights of quarters are normally distributed with a mean of 5.67 g and a
standard deviation 0.070 g. A vending machine will only accept coins weighing between
5.48 g and 5.82 g. What percentage of legal quarters will be rejected?
c. 1.96%
In a recent survey, 80% of the community favored building a police substation in their
neighborhood. If 15 citizens are chosen, what is the mean number favoring the substation?
c. 12
The tread life of a particular brand of tire is a random variable best described by a normal
distribution with a mean of 60,000 miles and a standard deviation of 1900 miles. What is
the probability a certain tire of this brand will last between 56,010 miles and 56,580 miles?
b. 0.0180
According to a 2007 report published by the National Center on Addiction and Substance
Abuse at Columbia University, 59% of teens have family dinners five or more times a
week, 13% of teens have used marijuana and the proportion of teens who have family
dinners 5 or more times a week or use marijuana is 0.64. What is the probability that a teen
has family dinners five or more times a week and uses marijuana? Hint. Use the addition
rules.
b. 0.08
A percentage distribution is given below for the size of families in one U.S. city. Size
Percentage 2 45.1 3 22.2 4 19.7 5 8.0 6 3.1 7+ 1.9 A family is selected at random. Find the
, probability that the size of the family is less than 6. Round your result to three decimal
places.
c. 0.950
The principal of a middle school claims that test scores of the seventh-graders at her school
vary less than the test scores of seventh-graders at a neighboring school, which have
variation described by σ = 14.7. Express the null hypothesis H0 and the alternative
hypothesis H1 in symbolic form.
b. H0: σ = 14.7 H1: σ < 14.7
To calculate the probability of obtaining three aces in eight draws of a card with
replacement from an ordinary deck, we would use the
b. binomial distribution.
The outcome of an experiment is the number of resulting heads when a nickel and a dime
are flipped simultaneously. What is the sample space for this experiment?
d. {0, 1, 2}
If we are using the normal approximation to determine the probability of at most 28
successes in a binomial distribution P(x ≤ 28) the normal distribution probability that is
used to make the estimate is
a. P(x ≤ 28.5).
The use of the Poisson distribution requires a value n which indicates a definite number of
independent trials.
a. False
The process of using sample statistics to draw conclusions about true population
parameters is called
d. statistical inference.
In 2006, the percent of the voting-age population that was registered to vote for the 50
states and the District of Columbia had a mean of 65% with a standard deviation of 7.1.
100% CORRECT ANSWERS!!
A study of 1000 randomly selected flights of a major airline showed that 782 of the flights
arrived on time. What is the probability of a flight arriving on time?
a. 391/500
Assume that the weights of quarters are normally distributed with a mean of 5.67 g and a
standard deviation 0.070 g. A vending machine will only accept coins weighing between
5.48 g and 5.82 g. What percentage of legal quarters will be rejected?
c. 1.96%
In a recent survey, 80% of the community favored building a police substation in their
neighborhood. If 15 citizens are chosen, what is the mean number favoring the substation?
c. 12
The tread life of a particular brand of tire is a random variable best described by a normal
distribution with a mean of 60,000 miles and a standard deviation of 1900 miles. What is
the probability a certain tire of this brand will last between 56,010 miles and 56,580 miles?
b. 0.0180
According to a 2007 report published by the National Center on Addiction and Substance
Abuse at Columbia University, 59% of teens have family dinners five or more times a
week, 13% of teens have used marijuana and the proportion of teens who have family
dinners 5 or more times a week or use marijuana is 0.64. What is the probability that a teen
has family dinners five or more times a week and uses marijuana? Hint. Use the addition
rules.
b. 0.08
A percentage distribution is given below for the size of families in one U.S. city. Size
Percentage 2 45.1 3 22.2 4 19.7 5 8.0 6 3.1 7+ 1.9 A family is selected at random. Find the
, probability that the size of the family is less than 6. Round your result to three decimal
places.
c. 0.950
The principal of a middle school claims that test scores of the seventh-graders at her school
vary less than the test scores of seventh-graders at a neighboring school, which have
variation described by σ = 14.7. Express the null hypothesis H0 and the alternative
hypothesis H1 in symbolic form.
b. H0: σ = 14.7 H1: σ < 14.7
To calculate the probability of obtaining three aces in eight draws of a card with
replacement from an ordinary deck, we would use the
b. binomial distribution.
The outcome of an experiment is the number of resulting heads when a nickel and a dime
are flipped simultaneously. What is the sample space for this experiment?
d. {0, 1, 2}
If we are using the normal approximation to determine the probability of at most 28
successes in a binomial distribution P(x ≤ 28) the normal distribution probability that is
used to make the estimate is
a. P(x ≤ 28.5).
The use of the Poisson distribution requires a value n which indicates a definite number of
independent trials.
a. False
The process of using sample statistics to draw conclusions about true population
parameters is called
d. statistical inference.
In 2006, the percent of the voting-age population that was registered to vote for the 50
states and the District of Columbia had a mean of 65% with a standard deviation of 7.1.
