QNT 561 FINAL EXAM – QUESTION AND ANSWERS
• A market researcher is interested in determining the average income for families in San Mateo County, California. To accomplish this, she takes a random sample of 300 families from the county and uses the data gathered from them to estimate the ave...
QNT 561 FINAL EXAM – QUESTION AND
ANSWERS
A market researcher is interested in determining the average income for families in San
Mateo County, California. To accomplish this, she takes a random sample of 300
families from the county and uses the data gathered from them to estimate the
average income for families of the entire county. This process is an example of
o Inferential statistics
If x is a binomial random variable with n=10 and p=0.8, what is the probability that x is
equal to 4?
o .0055
The number of bags arriving on the baggage claim conveyor belt in a 3 minute time
period would best be modeled with the _________.
o Poisson distribution
According to the central limit theorem, for samples of size 64 drawn from a population
with µ = 800 and σ = 56, the standard deviation of the sampling distribution of sample
means would equal _______.
o 7
Suppose a population has a mean of 400 and a standard deviation of 24. If a random
sample of size 144 is drawn from the population, the probability of drawing a sample
with a mean less than 402 is _______.
o 0.8413
If x is a binomial random variable with n=10 and p=0.8, the mean value of x is _____.
o 8
According to the central limit theorem, for samples of size 64 drawn from a population
with µ = 800 and σ = 56, the mean of the sampling distribution of sample means would
equal _______.
o 800
Completion time (from start to finish) of a building remodeling project is normally
distributed with a mean of 200 work-days and a standard deviation of 10 work-days. To
, be 99% sure that we will not be late in completing the project, we should request a
completion time of _______ work-days.
o 223
A researcher wants to determine the sample size necessary to adequately conduct a
study to estimate the population mean to within 5 points. The standard deviation of
population values is 80 and the researcher plans to use a 90% level of confidence. The
sample size should be at least _______.
o 44
The expected (mean) life of a particular type of light bulb is 1,000 hours with a standard
deviation of 50 hours. The life of this bulb is normally distributed. What is the
probability that a randomly selected bulb would last fewer than 940 hours?
o 0.1151
A large national company is considering negotiating cellular phone rates for its
employees. The Human Resource department would like to estimate the proportion of
its employee population who own an Apple iPhone. A random sample of size 250 is
taken and 40% of the sample own and iPhone. The 95% confidence interval to estimate
the population proportion is _______.
o 0.34 to 0.46
The mean life of a particular brand of light bulb is 1200 hours and the standard
deviation is 75 hours. Tests show that the life of the bulb is approximately normally
distributed. It can be concluded that approximately 68% of the bulbs will last between
_______.
o 1125 and 1275 hours
Consider the following null and alternative hypotheses.
Ho: ≤ 67
Ha: > 67
These hypotheses _______________.
o Are not constructed correctly
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