Exam 17: Sampling Distribution Models

Researchers believe that 7% of children have a gene that may be linked to a certain childhood disease.In an effort to track 50 of these children,researchers test 950 newborns for the presence of this gene.What is the probability that they do not find enough subjects for their study?

Based on past experience,a bank believes that 9% of the people who receive loans will not make payments on time.The bank has recently approved 300 loans.Describe the sampling distribution model of the proportion of clients in this group who may not make timely payments.

In a large statistics class,the professor has each student toss a coin 14 times and calculate the proportion of his or her tosses that were tails.The students then report their results,and the professor plots a histogram of these several proportions.Should a Normal model be used here?

Some experts estimate that the length of time people live in a house has a mean of 7.3 years and a standard deviation of 2.2 years.Explain why you could estimate the probability that 100 people selected at random had lived in their houses for an average of 9 years or more,but you could not estimate the probability that an individual had done so.

Suppose that the national mean weight for a three-year-old girl is 30 pounds with a standard deviation of 5 pounds.A pediatric office takes a random sample of 100 three-year-old girls,records their weights,and finds the mean.Describe the sampling distribution model of this mean.