cl. What is the upper bound of the confidence interval? e. Would it be reasonable to conclude that the population mean is 28 kg"? 3. Past surveys reveal that 30% of tourists going to Las Vegas to gamble during a weekend spend more than $1,000 (this is the population proportion). Management at one of the major casinos in Las Vegas would like to update this percentage. The new study is to use the 95% confidence level, and the maximum allowable error is to be 1% of the population proportion. What is the necessary sample size? (Hint: don't forget to make the percentages rates) 4. An owner of a local gas station wants to know the proportion of customers who use her pay-at- the~purnp feature. This feature allows customers to use a credit card at the pump and never enter the station. She surveyed 200 customers and found that 150 used the pay-atthe~pump feature. ' a. What is the sample proportion of people who use the pa-v-at-the-pump feature? b. Suppose she wants to create .a confidence level using the 90%'IEVeI of Confidence. What