In a random sample of five mobile devices, the mean repair cost was $65.00 and the standard deviation was $12.00. Assume the population is normally distributed and use a t-distribution to find the margin of error and construct a 95% confidence interval for the population mean. Interpret the results. The 95% confidence interval for the population mean p is ( 50.1, 79.9). (Round to two decimal places as needed.) The margin of error is $ (Round to two decimal places as needed.)

1. A recent study of 22 motorists showed that they spent an average of P750 per week. The standard deviation of the sample was P90. Find the 99% confidence interval of the true mean. Solution: 2. A sample of 15 National Collegiate Athletics Association (NCAA) basketball players had an average height of 6 feet with a sample standard deviation of 0.80 foot. Find the 90% confidence interval of the true mean height of all players. Solution:

A statistics class is estimating the mean height of all female students at their college. They collect a random sample of 42 female students and measure their heights. The mean of the sample is 65.3 inches and the sample standard deviation is 5.4 inches. Find the 90% confidence interval for the mean height of all female students in their school? Assume that the distribution of individual female heights at this school is approximately normal. 1. The t value is 1.3025 2. The standard error has a value of -- 3. The margin of error has a value of 4. Find the 90% confidence interval for the mean height of all female students in their school

The distribution of study times for first-year students follow a Normal distribution with a standard deviation σ = 48 minutes. Suppose a sample of 344 students found that the mean study time for these students was x¯= 170 minutes per week. Use this to find a 94.38% confidence interval to estimate the mean study time for all students. We are 94.38% confident that the mean study time for first-year students is between the following ( answer) minutes and  ( answer) minutes. The answer needs to be the mean study time for first-year students is between what amount of minutes and the following minutes.