sum of independent normal random variables

In a random sample of 25 trees, the variance in height was found to be 6.9. Find the 95% confidence interval for the standard deviation. Assume that the variable is normally distributed. => between 4.9 and 13.7 or between 4.2 and 13.4 or between 5.5 and 14.1 or between..

For any specific value of the independent variable, the values of the dependent variable y are normally distributed. This is called the __________ assumption. => independence or linearity or equal - variance or normality..

Which of the following are the assumptions for two-way ANOVA? I. All samples are drawn from normally distributed populations. II. All populations have a common variance. III. The groups must be equal in sample size. IV. Within each group, the observations were sampled randomly a..

The average number of hours a vehicle is in the parking lot of the company is 8. Assume the variable is normally distributed and the standard deviation is 2 hours. If 10 vehicles are selected at random, then find the probability that the mean number of hours they are k..

The average age of the employees in an organization is 34 years. Assume the variable is normally distributed and the standard deviation is 4. If 25 employees are selected at random, then find the probability that the sample mean age of the employees is less than 35 yea..

An automobile parts supplier wants to know how long car owners plan to keep their cars with them. A random sample of 20 car owners results in a standard deviation of 3.7 years. Find a 95% confidence interval for the variance and standard deviation. Assume that the variable is ..

According to a school report, the students in that school spend on an average 15 hours in front of computers. Assume the variable is normally distributed and the standard deviation is 2 hours. If 30 students are selected at random, then find the probability that the me..

The standard deviation of carbohydrates in a random sample of 15 different kinds of 4 oz patty sandwitches is 5.4 grams. At α = 0.01, test the hypothesis that the standard deviation is greater than 4.8 grams. What is the chi-square test value? [Assume that the variable is ..

A teacher wishes to estimate the average weight of 10 students of grade 6 taken randomly. The weight(in pounds) of the students are shown. Find the 99% confidence interval for the variance for the weights of students. Assume that the variable is normally distributed. 9..

A random sample of the assets (in millions of dollars) of 10 families of a colony is shown. Find the 80% confidence interval for the variance of the assets. Assume that the variable is normally distributed. 0.5 1 0.4 1.3 0.8 1.2 0.9 2 0.7 1.5 => between 0.158 and 0.529..