Exercise 18 Essay

We know that +/- 1.96 standard deviations from the mean will contain 95% of the values. So, we can get the standard deviation by:

2. In order to determine the average amount spent in November on Amazon.com a random sample of 144 Amazon accounts were selected. The sample mean amount spent in November was $250 with a standard deviation of $25. Assuming that the population standard deviation is unknown, what is a 95% confidence interval for the population mean amount spent on Amazon.com in November?

(21) You took a sample of size 21 from a normal distribution with a known standard deviation, . In order to find a 90% confidence interval for the mean, You need to find.

1. By hand, compute the mean, median, and mode for the following set of 40 reading scores:

18. Suppose that the scores of architects on a particular creativity test are normally distributed. Using a normal curve table, what percentage of architects have Z scores:

2. For the following set of scores, fill in the cells. The mean is 74.13 and the standard deviation is 9.98.

686, this leaves 5% of the scores outside this interval. Since a normal curve is symmetric, one-half of

5) Approximately ____% of the area under the normal curve is between μ - 3σ and μ + 3σ.

normally distributed, the 95% of all values will be within 2 standard deviations from the mean.

13. For the scores (3.0, 3.4, 2.6, 3.3, 3.5, 3.2): N = 6; Sum = 19; Mean = Sum/N = 19/6 = 3.17; Median = (2.6+3.3)/2 = 2.95; Sum of Squared Deviations = (3-3.17)2+(3.4-3.17)2+(2.6-3.17)2+(3.3-3.17)2+(3.5-3.17)2+(3.2-3.17)2 = 0.533; SD2 = SS/N = 0.533/6 = 0.089; SD = 0.089 = 0.298.

7. Assuming that the distribution is a normal curve, 99% of men were between what ages? Round your answer to two decimal places.

28. A loaf of bread is normally distributed with a mean of 22 oz and a standard deviation of 0.5 oz. What is the probability that a loaf is larger than 21 oz? Round your answer to four places after the decimal.

Feedback: 90% of 50 is 45, so we would expect 45 of the intervals to contain the true population mean.

Students Who Care is a student volunteer program in which college students donate work time in community centers for homeless people. Professor Gill is the faculty sponsor for this student volunteer program. For several years Dr. Gill has kept a record of the total number of work hours volunteered by s student in the program each semester. For students in the program, for each semester the mean number of hours was 29.1 hours with a standard deviation of 1.7 hours. Find an interval for the number of hours volunteered in which at least 88.9% of the students in this program would fit.

The first probability I will be figuring is the probability of a person being 16-21 years of age. The Second figure will show the probability of an individual’s overall satisfaction score of a 5.2 or lower. The third calculation I will be doing is finding the probability of a female working in the human resource department. Lastly I will show the probability of a salaried employee having an intrinsic score of 5 or more.