In a sample of 10 randomly selected women, it was found that their mean height was 63.4 inches. From previous studies, it is assumed that the standard deviation, σ, is 2.4 inches and that the population of height measurements is normally distributed. Construct the 99% confidence interval for the population mean height of women. If the level of confidence was lowered to 95%, what will be the effect on the confidence interval? If the sample size was doubled to 20 women, what will be the effect on the confidence interval?

A random sample of 10 children found that their average growth for the first year was 9.8 inches, with a standard deviation of 0.96 inches. Find the 85% confidence interval of the mean growth of all American children in the first year of life.What is the name of the confidence interval?

The mean length of 25 newly hatched iguanas is 7.47 inches with a standard deviation of 0.77 inches. Assume that the lengths of all newly hatched iguanas are normally distributed.   Step 1 of 2 :  Calculate the margin of error for a 98% confidence interval. Round your answer to two decimal places.

Assume that distances people driving to work are normally distributed. In a random sample of five people, the mean driving distance to work was 23 miles and the standard deviation was 6 miles. What is the length of the 95% confidence interval for the mean driving distance to work. Round to the nearest mile.

Christina wants to know the true average number of pages in a typical textbook. She randomly selects 196 books, and they have an average of 161 pages. Calculate a 90.3% confidence interval if you are given that the standard deviation for a single book is 75 pages.

A ecologist wishes to estimate the mean lifespan for a specific species of bird. Assume that bird lifespan is normally distributed and that each bird's lifespan is independent of all others. The researcher analyzes a random sample of n=7 deceased birds to find out how long they lived for. It is found that the mean lifespan in the sample is y= 5 4 years with standard deviation s=13 years. Choose the correct formula for a 95% confidence interval for the true mean lifespan. X± to.975,n O xt to.975,n-1 n-1 O none of these X+ Z0.975 O x+ to.975,n-1' O xt to.975,n-15

Karen wants to advertise how many chocolate chips are in each Big Chip cookie at her bakery. She randomly selects a sample of 63 cookies and finds that the number of chocolate chips per cookie in the sample has a mean of 9 and a standard deviation of 2. What is the 95% confidence interval for the number of chocolate chips per cookie for Big Chip cookies?

In a previous example, your sample consisted of 83 respondents. Suppose you doubled your sample size to 166 respondents and found that the average remained the same (39.04 hrs), as did the standard deviation (11.51 hrs). Calculate a 95 percent confidence interval of the true average in the population by using a new sample of 166 respondents. How did doubling sample size affect the results?

Karen wants to advertise how many chocolate chips are in each Big Chip cookie at her bakery. She randomly selects a sample of 78 cookies and finds that the number of chocolate chips per cookie in the sample has a mean of 19.3 and a standard deviation of 2.1.   Find a 80% confidence interval for the number of chocolate chips per cookie for Big Chip cookies?   Round your answers to one decimal place.