A random sample of students taking statistics was asked their GPA. The mean was 3.25 with...
A random sample of students was asked for the number of semester hours they are taking this semester. The standard deviation was found to be 4.7 semester hours. a) how many students should be included in the sample to be 90% sure that the sample mean is within 1 semester hour of the population mean for all students at this college?
If the mean GPA among students is 3.25 with a standard deviation of 0.75, and we select a random sample of 300 people, at what value for the sample mean would be greater than exactly 95% of possible sample means?
If the mean GPA among students is 3.25 with a standard deviation of 0.75, and we select a random sample of 300 people, at what value for the sample mean would be greater than exactly 95% of possible sample means?
3. A random sample of 45 students at a high school is collected and their GPA is recorded. The sample mean is computed to be 2.5 with a sample standard deviation of 1.3. i) Construct a 95% confidence interval for the mean GPA of all students at this school. For part (i), do not assume that GPA follows Normal distribution. ii) Construct an interval that is likely to include at least 90% of possible GPA values of students at this...
Arandom sample of 100 students had a mean grade point average (GPA) of 3.2 with a standard error of 0.02. Given below are the 90%, 95%, 98% and 99% confidence intervals (not necessarily in that order) for the mean GPA for all students. Which interval would represent the 95% confidence interval? (3.15, 3.25) (3.17.3.23) (3.16, 3.24) (3.14, 3.26)
A random sample of 15 night students was taken with a sample mean GPA of 2.82 and a standard deviation of 0.05. A random sample of 17 day students was taken with a sample mean GPA of 2.79 and a standard deviation of 0.07. Test the claim that the mean GPA of night students (un) is greater than than the mean GPA of day students (up) at a = 0.10. Assume that the data come from normal populations with unequal...
Students in an introductory statistics class were asked to report the age of their mothers when they were born. Summary statistics include Sample size: 28 students Sample mean: 29.643 years Sample standard deviation: 4.564 years a. Calculate the standard error of this sample mean. b. Determine and interpret a 90% confidence interval for the mother’s mean age (at student’s birth) in the population of all students at this university. c. How would a 99% confidence interval compare to the 90%...
Students in an introductory statistics class were asked to report the age of their mothers when they were born. Summary statistics include Sample size: 28 students Sample mean: 29.643 years Sample standard deviation: 4.564 years a. Calculate the standard error of this sample mean. b. Determine and interpret a 90% confidence interval for the mother’s mean age (at student’s birth) in the population of all students at this university. c. How would a 99% confidence interval compare to the 90%...
2. Suppose that a random sample of 41 state college students is asked to measure the length of their right foot in centimeters. A 90% confidence interval for the mean foot length for students at this university turns out to be (21.709, 25.091). If we now calculated a 95% confidence interval, would the new confidence interval be wider than or narrower than or the same as the original? b. Suppose two researchers want to estimate the proportion of American college...
4. A survey asked a random sample of 363 first-year students how many hours they studied during a particular week. The mean was 15.3 hours. Suppose we know that the population standard deviation is 8.5 hours. Construct a 90%, 95% and 99% confidence interval for the mean study time of all first year students at this university. Interpret the 90% confidence interval.