normal distribution

The standard deviation of the hemoglobin values (g/100ml) of 10 children is 1.7. Find the 99% confidence interval for the variance and standard deviation. Assume that the variable is normally distributed. => 1.26 < σ 2 < 14.75 ; 1.12 < σ < 3.84 or 1.1 <..

The basic assumption(s) for estimating the difference between two variances is/are: I. The samples must be dependent on each other. II. The samples must be independent of each other. III. The populations from which the samples were obtained must be normally distributed. IV. The ..

Assume that the weights of 3,000 students at a university are normally distributed with mean 150 pounds and a standard deviation of 7 pounds. If 100 samples of 30 students each are obtained, then what would be the expected mean and standard deviation of the resulting sampling ..

A survey asks 'How much time do you spend in front of the TV in one week? Suppose the responses are normally distributed, the mean is 10 hours and the standard deviation is 2 hours. What value in hours is one standard deviation above the mean, and one standard deviation below th..

The local authorities in a certain city install 1600 electric lamps in the streets of the city. If the lamps have a mean life rate of 1000 burning hours, with a standard deviations of 150 hours, find the value of - 2 standards deviations form the mean. Assume that the lines of the lamps are no..

Assume that the weights of 3,000 students at a university are normally distributed with mean 150 pounds and a standard deviation of 2.72 pounds. How many samples would you expect to find the mean between 147 and 155 pounds? => 83 or 82 or 84 or 81..

The mean weight of 400 students at a certain college is 150 lb, and the standard deviation is 15 lb. Assuming that the weights are normally distributed, how many students weigh greater than 120 lb and less than 155 lb? => 242 or 191 or 158 or 51..

The heights of a group of young women aged 16 - 25 years was found to be normally distributed with a mean of 62.4 inches and a standard deviation of 1.5 inches. For what value of height will the population of women be more than 15% . => 63 inches or 62 inches or 63.9 inches or 6..

What is the area under the normal distribution curve to the right of z = 1.56? => 5.94% or 55.94% or 94.06% or 44.96%..

Find the area under the normal distribution curve to the right of z = - 0.97. => 83.4% or 16.6% or 33.4% or 66.6%..