Business Statistics: Confidence Intervals and Control Charts

BUSINESS STATISTICS
STUDENT NAME/ID
[Pick the date]

Question 1 “SHOPPING DOWNTOWN”
(a) The population would consist of all cars that are brought in all the service departments. The
sample would comprise of the cars that are brought in the given service department. The
underlying parameter refers to the proportion of the above cars which have dents that can be
easily prepared. In order to estimate the confidence interval, the given binomial distribution
would be converted into a normal distribution and using Z statistic, the 95% confidence interval
can be estimated using Excel as an enabling tool.
(b) The population would comprise of all the customers who shop at the given supermarket is
conducting the survey. The sample would comprise of the 325 customers who have actually
responded. The parameter of interest is the proportion of shoppers at this supermarket who find
the experience more pleasing that the nearby store. In order to estimate the confidence interval,
the given binomial distribution would be converted into a normal distribution and using Z
statistic, the 95% confidence interval can be estimated using Excel as an enabling tool.
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(c) The population would comprise of all the visitors who are eligible to participate in the poll
and tend to visit the area where poll is being held. The sample is the 223 responses that have
been collected on day one. The parameter of interest is the average daily TV watching duration
for the population. Since the standard deviation is not known, hence it would be correct to deploy
the T statistics for estimating the confidence interval as indicated below.
(d) The population would comprise of all the customers who have assumed loan. The sample
would comprise of the given 1000 customers. The parameter of interest is to estimate the
proportion of customers who would default on their loans. In order to estimate the confidence
interval, the given binomial distribution would be converted into a normal distribution and using
Z statistic, the 95% confidence interval can be estimated using Excel as an enabling tool
Question 2 “INSULATOR PROBLEM”
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