12. A random sample is obtained from a normal popula- tion with a mean of µ = 95 and a standard deviation of o = 40. The sample mean is M = 86. a. Is this a representative sample mean or an extreme value for a sample of n = 16 scores? b. Is this a representative sample mean or an extreme value for a sample of a=100 scores? ONOR

Suppose x has a normal distribution with mean ? = 53 and standard deviation ? = 7.Describe the distribution of x values for sample size n = 4. (Round ?x to two decimal places.) ?x =  ?x =  Describe the distribution of x values for sample size n = 16. (Round ?x to two decimal places.) ?x =  ?x =  Describe the distribution of x values for sample size n = 100. (Round ?x to two decimal places.) ?x =  ?x =

This assignment is worth 1 points. The extra point will be added to your overall course grade. For example: if you receive an 88% in the course you can receive up to 1 point giving you a new score of 89%. The following rubric will be used.  0.25 point for drawing the normal distribution curve with the mean value labeled on the curve and the appropriate area shaded. 0.25 point for determining the value of the standard deviation of the sample mean.  0.5 point for finding the correct probability.   All work must be shown in order to receive any credit.  Please upload your completed assignment here.    The length of time taken on the SAT for a group of students is normally distributed with a mean of 2.5 hours and a standard deviation of 0.25 hours. A sample size of n = 60 is drawn randomly from the population. Find the probability that the sample mean is between two hours and three hours.

6.2 The Standard Normal Distribution Table: Z-score and Probability In the country of United States of Heightlandia, the height measurements of ten-year-old children are approximately normally distributed with a mean of 53.7 inches, and standard deviation of 5.1 inches. What is the probability that the height of a randomly chosen child is between 40.95 and 43.35 inches? Probability = (Use 4 decimal places.)

A population has a mean µ = 87 and a standard deviation à = 23. Find the mean and standard deviation of a sampling distribution of sample means with sample size n = 257. ox = (Simplify your answer.) (Type an integer or decimal rounded to three decimal places as needed.) 33

In a population of a certain species of newt, the mean length of the newts is μ= 63 inches and the standard deviation is σ= 3.4 inches. You collect a random sample of n=16 newts. The bell curve below represents the distribution of these sample means. The scale on the horizontal axis is the standard error of the sampling distribution. Complete the indicated boxes, correct to two decimal places. mean of distribution= standard error=       Note: The left box is 2 standard errors below the mean. The middle box is the mean. The right box is 2 standard errors above the mean.

3.2.41 The blood platelet counts of a group of women have a bell-shaped distribution with a mean of 253.3 and a standard deviation of 66.3. (All units are 1000 cells/ul.) Using the empirical rule, find each approximate percentage below. a. What is the approximate percentage of women with platelet counts within 2 standard deviations of the mean, or between 120.7 and 385.9? Question Help ▼ b. What is the approximate percentage of women with platelet counts between 187.0 and 319,6? a. Approximately % of women in this group have platelet counts within 2 standard deviations of the mean, or between 120.7 and 385.9. (Type an integer or a decimal. Do not round.) Enter your answer in the answer box and then click Check Answer. Check Answer Clear All 1 part remaining MacBook Air %23 6. E R Q D M

15. A sample has a mean M = 75. In the sample, a score of X = 95 corresponds to z = 2.5 What is the standard deviation for the sample?

12. A population forms a normal distribution with a mean of u = 55 and a standard deviation of o = 12. For each of the following samples, compute the z-score for the sample mean. a. M = 58 for n = 4 scores %3D b. M 58 for n = 16 scores c. M = 58 for n = 36 scores

Exhibit 9-41 A random sample of 9 students selected from the student body of a high school had an average age of 14 years. We want to determine if the average age of all the students at the high school is significantly different from 13. Assume the distribution of the population of ages is normal with a standard deviation of 1 year. Refer to Exhibit 9-41. What is the p-value for this test? 0.00135 0.0027 1.96 0.0045