Suppose the preliteracy scores of three-year-old students in the United States are normally distributed. Shelia, a...
Suppose the preliteracy scores of three-year-old students in the United States are normally distributed. Shelia, a preschool teacher, wants to estimate the mean score on preliteracy tests for the population of three-year-olds. She draws a simple random sample of 20 students from her class of three-year-olds and records their preliteracy scores (in points). 74, 79, 83, 85, 88, 90, 94, 95, 95, 97,99, 99, 100, 103, 105, 105, 106, 107, 107, 108 Click to download the data in your preferred...
Question 7 2 pts Suppose scores on exams in statistics are normally distributed with an unknown population mean and a population standard deviation of 6 points. A random sample of 50 scores is taken and gives a sample mean (sample mean score) of 80. Find a 95% confidence interval for the true (population mean of statistics exam scores Lower Confidence Level – Upper Confidence Level (Round to only 1 decimal place) **NOTE: apparently some Ti calculators only display 3 decimal...
The scores on an examination in biology are approximately normally distributed with mean 500 and an unknown standard deviation. The following is a random sample of scores from this examination. 419, 455, 479, 535, 540, 607 Find a 99% confidence interval for the population standard deviation. Then complete the table below. Carry your intermediate computations to at least three decimal places. Round your answers to at least two decimal places (If necessary, consult a list of formulas-) What is the...
1 2 3 5 6 The scores on an examination in psychology are approximately normally distributed with mean 500 and an unknown standard deviation. The following is a random sample of scores from this examination 410,438, 469, 501, 527, 539,586 Find a 90% confidence interval for the population standard deviation. Then complete the table below Carry your intermediate computations to at least three decimal places. Round your answers to at least two decimal places What is the lower limit of...
The standard deviation of test scores on a certain achievement test is 11.1. A random sample of 60 scores on this test had a mean of 75.4. Based on this sample, find a 95% confidence interval for the true mean of all scores. Then complete the table below. Carry your intermediate computations to at least three decimal places. Round your answers to one decimal place. What is the lower limit of the 95% confidence interval? What is the upper limit...
We considered the differences between the reading and writing scores of a random sample of 200 students who took the High School and Beyond Survey in Exercise 5.21. The mean and standard deviation of the differences are x̄read-write = -0.545 and 8.887 points respectively. (a) Calculate a 95% confidence interval for the average difference between the reading and writing scores of all students. lower bound: points (please round to two decimal places) upper bound: points (please round to two decimal...
The results of a study of 258 students who paid a private tutor to help them improve their scores on a standardized test are shown below. The changes in both the Mathematics and Verbal scores for these students are reproduced in the table. Complete parts a through c below. Test score improvements Math Verbal Mean change in score 18 8 Standard deviation of score changes 67 50 a. Construct and interpret a 95% confidence interval for the population mean change...
please show how its done on TI-64 1. SAT scores are distributed with a mean of 1,500 and a standard deviation of 300. You are interested in estimating the average SAT score of first year students at your college. If you would like to limit the margin of error of your 95% confidence interval to 25 points, how many students should you sample? 3. If n=31, ¯xx¯(x-bar)=36, and s=6, construct a confidence interval at a 98% confidence level. Assume the...
The results of a study of 258 students who paid a private tutor to help them improve their scores on a standardized test are shown below. The changes in both the Mathematics and Verbal scores for these students are reproduced in the table. Complete parts a through c below. Test score improvements Math Verbal Mean change in score 18 8 Standard deviation of score changes 67 50 a. Construct and interpret a 95% confidence interval for the population mean change...
The Weschler Intelligence Scale for Children (WISC) is an intelligence test designed for children between the ages of 6 and 16. The test is standardized so that the mean score for all children is 100 and the standard deviation is 15. Suppose that the administrators of a very large and competitive school district wish to estimate the mean WISC score for all students enrolled in their programs for gifted and talented children. They obtained a random sample of 40 students...