Answer to Question #258864 in Statistics and Probability for Ronald

Question

Question

Q4

In a random sample of 400 students and 600 graduates who studies a given pre-

requisite course upon entry into university, 100 students and 300 graduates indicated 

that they found it helpful. Construct a 99% confidence interval for the difference in 

proportions of all students and all graduates who took a given pre-requisite course and 

found it helpful.

b) The standard deviation of the running time of a sample of 200 fuses was found to be 

100 hours. Find a 99% confidence interval for the standard deviation of all such fuses.

c) Two samples, sample one of size 16 and sample two of size 10, respectively, are drawn 

at random from two populations that are normally distributed. If their variances are 

found to be 24 and 18, respectively, find:

i. 98% confidence interval for the ratio of the variances.

ii. 90% confidence interval for the ratio of the variances.