A researcher is interested in estimating the savings account balance of customers at a large bank. She obtains the savings account balance of a random sample of 30 customers. A 95% confidence interval for the mean savings account balance of bank customers is found to be ($3402.08, $4142.75). Which of the following would produce a confidence interval with a smaller margin of error than this 95% confidence interval? Group of answer choices Obtain the savings account balances of only 10 bank customers rather than 30, because 10 are likely to be more uniform than 30. Compute a 99% confidence interval rather than a 95% confidence interval. Obtain the balances of 90 bank customers rather than 30. None of the these answers.