A sample of 94 WCC students found mean age 24.7 years old with standard deviation 7.9...

A sample of 94 WCC students found mean age 24.7 years old with standard deviation 7.9 years old.

(a) Make a 90% confidence interval for the mean age of all WCC students. Interpret the interval.

(b) Redo (a) if instead of 94 students, only 13 students had been sampled. Do not interpret the interval.

Solutions

Expert Solution

Solution:- Given that n = 94, X = 24.7, s = 7.9

(a) 90% Confidence interval for the mean age is (23.35,26.05)

interpretation:
if repeated samples of same size were taken and the 90% confidence interval was computed for each smple, 90% of the intervals would contain mean. we are 90% certain that the interval (23.35,26.05) contains the population mean age.

(b) for n = 13,

90% Confidence interval for the mean age is (20.80,28.61)

orchestra answered 1 year ago

Next > < Previous

Related Solutions

A random sample of 150 WCC students found that 68 of them were Latino/a. a) At...

A random sample of 150 WCC students found that 68 of them were Latino/a. a) At the 5% level of significance can we prove that over 40% of all WCC students are Latino/a? State and test appropriate hypotheses. State conclusions. b) Find the p-value of the test in (a). c) If an error was made in (a), what type was it?

Assume the average age of an MBA student is 34.9 years old with a standard deviation...

Assume the average age of an MBA student is 34.9 years old with a standard deviation of 2.5 years. a) Determine the coefficient of variation. b) Calculate the z-score for an MBA student who is 29 years old. c) Using the empirical rule, determine the range of ages that will include 99.7% of the students around the mean. d) Using Chebyshev's Theorem, determine the range of ages that will include at least 91% of the students around the mean. e)...

Assume the average age of an MBA student is 30.7 years old with a standard deviation...

Assume the average age of an MBA student is 30.7 years old with a standard deviation of 2.2 years. a) Determine the coefficient of variation. b) Calculate the z-score for an MBA student who is 26 years old. c) Using the empirical rule, determine the range of ages that will include 95% of the students around the mean. d) Using Chebyshev's Theorem, determine the range of ages that will include at least 94% of the students around the mean. e)...

A population has a mean age of 50 years and a standard deviation equal to 10...

A population has a mean age of 50 years and a standard deviation equal to 10 years. To study the population, you decide to sample 36 individuals and measure their age. What is the probability that a sample mean age is between 47.5 and 52.5 years? Answer What is the probability of selecting a sample of 36 individuals that has a sample mean of 55 years or more? Answer What is the probability of selecting a sample of 36 individuals...

A sample of 90 WCC students found that 57 of them were female. a)Find a point...

A sample of 90 WCC students found that 57 of them were female. a)Find a point estimate for the percentage of all WCC students that are female. b)Find the 95% margin of error for the estimate. c)Make a 95% confidence interval for the percentage of all WCC students that are female. Interpret the interval. 2. A sample of 84 WCC students found mean age 24.7 years old with standard deviation 7.9 years old. a) Make an 80% confidence interval for...

Suppose the age is normally distributed with a mean of 62 years old and a standard...

Suppose the age is normally distributed with a mean of 62 years old and a standard deviation of 3.7 years. 1. One of the patient’s age of diagnosis was 1.63 standard deviations above the mean. What was this patient’s age when he was diagnosed? 2.Using Z > 2 as a criterion for an outlier, what is the minimum sample size such that a sample mean of 62.5 years would be classified as an outlier?

The age of all farmers are normally distributed with a mean 48 years old and standard...

The age of all farmers are normally distributed with a mean 48 years old and standard deviation 12 years old. Part A About % of all farmers are older than 16 years old. (Rounding the percentage to 2 decimal places if possible) Part B About % of all farmers are younger than 38 years old. (Rounding the percentage to 2 decimal places if possible) Part C About % of all farmers are between 28 years old and 61 years old. (Rounding the percentage...

The mean age of random university, College students in a previous term was 26.6 years old....

The mean age of random university, College students in a previous term was 26.6 years old. An instructor thinks the mean age for online students is older than 26.6. She randomly surveys 60 online students and finds that the sample mean is 29.6 with a standard deviation of 2.1. Conduct a hypothesis test at the 5% level. Note: If you are using a Student's t-distribution for the problem, you may assume that the underlying population is normally distributed. (In general,...

Item Sample Mean 1 Population standard deviation of 1 n1 Sample Mean 2 Population Standard Deviation...

Item Sample Mean 1 Population standard deviation of 1 n1 Sample Mean 2 Population Standard Deviation 2 n2 7 18 6 169 12 12 121 0.01 Perform a Two-tailed hypothesis test for two population means.

A sample of 225 American males showed a mean lifetime of 69.8 years, standard deviation of...

A sample of 225 American males showed a mean lifetime of 69.8 years, standard deviation of 4.3 years. Give 99.73% confidence limits for the mean lifetime of American males.

Subjects