When we go to the table, we find that the value 0.90 is not there exactly, however, the values 0.8997 and 0.9015 are there and correspond to Z values of 1.28 and 1.29, respectively (i.e., 89.97% of the area under the standard normal curve is below 1.28). Subsequently, one may also ask, what is the z score for 92 confidence interval? Common confidence levels and their critical values Confidence Level One may also ask, what is the z score for 93 confidence interval? B. If 36 men are randomly selected, find the probability that they have a mean height greater than 70.5 inches.Likewise, people ask, what is the z score for 90 percent?Īnd a standard deviation (also called the standard error): For the standard normal distribution, P(-1.96 < Z < 1.96) = 0.95, i.e., there is a 95% probability that a standard normal variable, Z, will fall between -1.96 and 1.96.Ĭonfidence Intervals. Question 4 Provide an appropriate response.Assume that the heights of men are normally distributed with a mean of 69.5 inches and a standard deviation of 2.1 inches. Find the x-value that corresponds to the z-score 2.33. Question 3 Provide an appropriate response.The scores on a mathematics exam have a mean of 70 and a standard deviation of 5. If a sample of 50 individuals is randomly selected, find the probability that the mean of the sample will be less than 200 pounds. The average number of pounds of red meat a person consumes each year is 196 with a standard deviation of 22 pounds (Source: American Dietetic Association). Question 2 Provide an appropriate response. Question 1 Provide an appropriate response. Use a standard normal table to find the z-score that corresponds to the 80 th percentile. Which of the following mean expenses would be considered unusual? Random samples of size 20 are drawn from this population and the mean of each sample is determined. Question 8 Provide an appropriate response.The distribution of room and board expenses per year at a four-year college is normally distributed with a mean of $5850 and standard deviation of $1125. Question 7 Provide an appropriate response.įind the z-score for which 99% of the distribution’s area lies between -z and z. If a sample of 50 individuals is randomly selected, find the probability that the mean of the sample will be greater than 200 pounds. Question 6 Provide an appropriate response.The average number of pounds of red meat a person consumes each year is 196 with a standard deviation of 22 pounds (Source: American Dietetic Association). įind the z-score that has 84.85% of the distribution’s area to its right. Question 4 Provide an appropriate responseFind the z-score that is greater than the mean and for which 70% of the distribution’s area lies to its left. What is the cutoff salary for teachers in the top 10%? Question 3 Provide an appropriate response.Assume that the salaries of elementary school teachers in the United States are normally distributed with a mean of $29,000 and a standard deviation of $2000. What is the cutoff salary for teachers in the bottom 10%? Question 2 Provide an appropriate response.Īssume that the salaries of elementary school teachers in the United States are normally distributed with a mean of $37,000 and a standard deviation of $5000. įor the standard normal curve, find the z-score that corresponds to the 90 th percentile. Question 7 Provide an appropriate response.The scores on a mathematics exam have a mean of 70 and a standard deviation of 5. Question 6 Provide an appropriate response.įind the z-score that corresponds to the given area under the standard normal curve. It does this for positive values of z only (i.e., z-values on the right-hand side of the mean). If 100 people are randomly selected, find the probability that their mean blood pressure will be less than 117. The standard normal distribution table provides the probability that a normally distributed random variable Z, with mean equal to 0 and variance equal to 1, is less than or equal to z. Question 5 Provide an appropriate response.Īssume that blood pressure readings are normally distributed with a mean of 115 and a standard deviation of 8. If 100 women are randomly selected, find the probability that they have a mean height greater than 63.0 inches. Question 4 Provide an appropriate response.Assume that the heights of women are normally distributed with a mean of 63.6 inches and a standard deviation of 2.5 inches. Question 3 Provide an appropriate response Find the z-scores for which 90% of the distribution’s area lies between -z and z. Question 2 Provide an appropriate response Find the z-score that has 84.85% of the distribution’s area to its right. Use a standard normal table to find the z-score that corresponds to the cumulative area of 0.7019. Question 1 Provide an appropriate response.
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