1. All else being equal, when computing a confidence interval, as the sample size, n, increases, the margin of error_______. Choose the best answer

		decreases.
		always doubles.
		increases.
		stays the same.

2.

Dr. Mack Lemore, an expert in consumer behavior, wants to estimate the average amount of money that people spend in thrift shops. He takes a small sample of 8 individuals and asks them to report how much money they had in their pockets the last time they went shopping at a thrift store. Here are the data: 23, 40, 11, 24, 22, 11, 25, 24. Find the upper bound of a 95% confidence interval for the true mean amount of money individuals carry with them to thrift stores, to two decimal places. Take all calculations toward the final answer to three decimal places.

3. MXG corporation sells buckets of a substance used in oil drilling. Quality control procedures require that regular samples be taken to ensure that the mean weight of the buckets meets specifications. Based on a sample of 10 buckets taken from the production line, the quality control inspector found that the mean weight of the buckets was 32 pounds, with a standard deviation of 0.2 pounds. Calculate a 99% confidence interval for the true mean weight of the buckets that MXG produces. Take all calculations to three (3) decimal places, and report your answer to one (1) decimal place (that is, to the nearest tenth of a pound).

4.

A manufacturer of smartphones is interested in designing a new phone around the way a typical customer would use it. One of the most important characteristics for any smartphone is battery life since every activity on a smartphone draws power from the battery in some way. This is especially true for those who use their phones heavily for texting, social media, gaming, etc.

In a marketing research survey, the manufacturer asked a random sample of 25 smartphone owners who consider themselves "heavy users" to run an app on their phone that would record the time the phone is used for various activities (but, for privacy reasons, not record what that activity was).

The company decides to first examine the total minutes used in all activities. The sample mean number of minutes of total use from the 25 users was 119.4, with a standard deviation of 29.5 minutes. Find the upper bound of a 90% confidence interval for the true mean total time that smartphones are used by the population of "heavy users" to one decimal place. Take all calculations toward the answer to three (3) decimal places.

5. Dr. Mack Lemore, an expert in consumer behavior, wants to estimate the average amount of money that people spend in thrift shops. He takes a small sample of 8 individuals and asks them to report how much money they had in their pockets the last time they went shopping at a thrift store. Here are the data: 23.09, 34.76, 27.46, 12.95, 31.17, 22.59, 17.51, 20.11. Find the lower bound of a 98% confidence interval for the true mean amount of money individuals carry with them to thrift stores, to two decimal places. Take all calculations toward the final answer to three decimal places.