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Which muscular layer of the esophagus helps propel food down through coordinated contractions?

A container of soda is supposed to contain 1000 milliliters of soda. A quality control manager wants to be sure that the standard deviation of the soda containers is less than 20 milliliters. He randomly selected 10 cans of soda and found the mean was 997 milliliters and the standard deviation of 18 milliliters. Does this suggest that the variation in the soda containers is at an acceptable level (less than 20 milliliters)?  Assume that the amount of soda contain is normally distributed.  Use

In the previous year the proportion of deposits in checking accounts at a certain bank that were made electronically was 35%. The bank wishes to determine if the proportion is higher this year. It examined 1200 deposit records and found that 456 were electronic. Determine, at the 1% level of significance, whether the data provide sufficient evidence to conclude that more than 35% of all deposits to checking accounts are now being made electronically. [Make sure to provide the null and alternative hypotheses, check requirements to provide the appropriate test statistic, p-value or critical value, decision, and conclusion.]

In a random sample of 50 dog owners enrolled in obedience training, it was determined that the mean amount of money spent per owner was $109.33 per class and the standard deviation of the amount spent per owner is $28.17, construct and interpret a 90% confidence interval for the mean amount spent per owner for an obedience class.

The tread life of a particular brand of tire is a random variable best described by a normal distribution with a mean of 65,000 miles and a standard deviation of 3200 miles. What is the probability a particular tire of this brand will last longer than 70,000 miles? What warranty should the company use if they want 95% of the tires to outlast the warranty?

A nationwide study indicated that 83% of college students with cell phones listen to music with their phones.  A simple random sample of 196 college students with cell phones is obtained. a) Describe the sampling distribution of the sample proportion of college students with cell phones who listen to music with their phones. b) What is the probability that 170 or more college students in the sample listen to music with their cell phones?

In a random sample of 50 dog owners enrolled in obedience training, it was determined that the mean amount of money spent per owner was $109.33 per class and the standard deviation of the amount spent per owner is $28.17, construct and interpret a 99% confidence interval for the mean amount spent per owner for an obedience class.

Assume that the weight loss for the first month of a diet program varies between 5 pounds and 50 pounds, and is spread evenly over the range of possibilities, so that there is a uniform distribution.  What is the probability of the weight loss more than 35 pounds?

In a simple random sample of 300 employed people, 78 said that they bring work home with them at least occasionally. a) Construct and interpret a 96% confidence interval for the proportion of all employed people who bring work home with them at least occasionally. b) Find the minimum sample size would be needed for a 99% confidence interval with the margin of error of 0.025.

A final exam for Math 50 has a mean of 76.9 with standard deviation of 7.7.  If 49 students are randomly selected, a) describe the sampling distribution of the sample mean. b) find the probability that the mean of the 49 students test scores is at least 80.