Statistics class - Assignment Example

The manager’s speculation that the true population proportion of customers who live in urban area exceeds 40% does not seem to be correct as the hypotheses testing shows that the proportion of customers may be around 40% or lower. The confidence interval also has a very high range of values and so it means that the proportion can be between 30% to 58% of the customers. The manager’s speculation that the average number of years lived in the current home is less than 13 years does not seem to be correct.

The mean number of years lived in the current home is around 12.26 years. This shows that an average customer does seem to spend at least a decade in the same house and because of that will be more inclined to shopping things from the same department store over the years because of convenience. The confidence interval is (10.85, 13.67) and we can be 95% confident that on average a customer would live in the same house for an x number of years that is between those two intervals. The manager’s speculation that the average credit balance for suburban customers is more than $4300 does seem to be correct.

The null hypothesis was rejected as the test statistic was higher than z-value during the hypotheses testing. It shows that urban customers also have a high amount of credit against their name and we can be 95% confident that on average an urban customer’s credit amount would lie between $4299.65 and $5051.02. 5) Because the sample size of the data is large enough (n> 30), the Central Limit Theorem will apply, and no assumptions have to be made about the population of the credit customers. The sampling distribution of the sample mean of credit customers will be approximately normal regardless of the distribution of individual credit customers.

The confidence interval level is (0.30, 0.58). It means that we are 95% confident that population proportion of customers who live in urban area lie between the lower and the upper limit of the