a. less than 95?
b. between 95 and 97.5?
c. above 102.2?
d. There is a 65% chance that X is above what value?

Time spent using e-mail per session is normally distributed, with a population mean of 8 minutes and standard error of the mean is 2 minutes. If you select a random sample of 25 sessions,

a. what is the probability that the sample mean is between 7.8 and 8.2 minutes?
b. what is the probability that the sample mean is between 7.5 and 8 minutes?
c. If you select a random sample of 100 sessions, what is the probability that the sample mean is between 7.8 and 8.2 minutes?
d. Explain the difference in the results of (a) and (c).

You plan to conduct a marketing experiment in which students are to taste one of two different brands of soft drink. Their task is to correctly identify the brand tasted. You select a random sample of 200 students and assume that the students have no ability to distinguish between the two brands. (Hint: If an individual has no ability to distinguish between the two soft drinks, then the two brands are equally likely to be selected.)

a. what is the probability that the sample will have between 50% and 60% of the identifications correct?
b. the probability is 90% that the sample percentage is contained within what symmetrical limits of the population percentage?
c. what is the probability that the sample percentage of correct identifications is greater than 65%?
d. which is more likely to occur more than 60% correct identifications in the sample of 200 or more than 55% correct identifications in a sample of 1,000? Explain.

The fill amount of bottles of a soft drink is normally distributed, with a mean of 2.0 liters and a standard deviation of 0.05 liter. If you select a random sample of 25 bottles, what is the probability that the sample mean will be

a. between 1.99 and 2.0 liters?
b. below 1.98 liters?
c. greater than 2.01 liters?
d. the probability is 99% that the sample mean amount of soft drink will be at least how much?

Solution Summary

The solution provides step by step method for the calculation of probability using the Z score. Formula for the calculation and Interpretations of the results are also included.

Which of the following is true about the samplingdistribution of the samplemean?
A. The mean of the samplingdistribution is always "u"
B. The standard deviation of the samplingdistribution is always "o"
C. The shape of the samplingdistribution is always approximately normal
D. All of the above

The amount of pyroxidine (in grams) per multiple vitamin is normally distributed with a mean = 110 grams and a variance = 25 grams. A sample of 25 vitamins is to be selected. What is the probability that the samplemean will be greater than 100 grams?

For a sample size 16, the samplingdistribution of the mean will be approximately normally distributed:
A. regardless of the shape of the population
B. if the shape of the population is symmetrical
C. if the sample standard deviation is known
D. if the sample is normally distributed

6.30
Given a population in which the proportion of items with a desired attribute is p=0.25, if a sample of 400 is taken:
a. What is the standard deviation of the samplingdistribution of _
P?
b. What is the probability the propo

For one quantitative coures in a college with 10,000 students, it is calculated that students test scores are normally distributed with a mean of 80 and a standard deviateion of 16. Assume now we randomly select a sample of 64 students test scores.
a.) What is the probability that the average test score of the sample selecte

Suppose the annual consumption of chicken mean is 20.84 pounds per person, and that the standard deviation for the consumption of chicken per person is 9.193 pounds. The mean weight of chicken consumed for a sample of 200 randomly selected people is one value of many that form the samplingdistribution of samplemeans.
Descri

The diameter of Ping-Pong balls manufactured at a large factory is approximately normally distributed, with a mean of 1.30 inches and a standard deviation of 0.04 inch. If you slect a random sample of 16 Ping-Pong balls,
a) What is the samplingdistribution of the mean?
b) What is the probability that the samplemean is les

The proportion of individuals insured by the All-Driver Automobile Insurance Company who received at least one traffic ticket during a five-year period is .15.
1. Show the samplingdistribution of p if a random sample of 150 insured individuals is used to estimate the proportion having received at least one ticket.
2. What i

Suppose the annual consumption of chicken mean is 20.84 pounds per person and that the standard deviation for the consumption of chicken per person is 9.193 pounds. The mean weight of chicken consumed for a sample of 200 randomly selected people is one value of many that form the samplingdistribution of samplemeans.
Descri

According to the College Board's report, the average tuition and fees at four year private colleges and universities in the United States was $18,273 for the academic year 2002 - 2003 and the standard deviation was $2100. For a random sample of 100 four year private U.S. colleges, answer the following:
a. What is the mean of