(A) Find a 95% Confidence Interval for the Mean Account

question 20

Essay

(A) Find a 95% confidence interval for the mean account balance on this store's credit card (the t-multiple with 39 degrees of freedom is 2.0227).
(B) What sample size would be needed to ensure that we could estimate the true mean account balance and have only 5 chances in 100 of being off by more than $100?

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Definitions:

Hypothesis

A proposed explanation for a phenomenon, made as a starting point for further investigation, which can be tested through experimentation or observation.

Principle of Falsifiability

A criterion for scientific theories proposed by Karl Popper, stating that for a theory to be considered scientific, it must be able to be proven false.

Replication

The process of repeating a study or experiment to verify its findings.

Theory

A well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment.