6. Refer to question 2. How many nails should be sampled from each machine if a 95% confidence interval for the true dif

[answerhappygod]

6 Refer To Question 2 How Many Nails Should Be Sampled From Each Machine If A 95 Confidence Interval For The True Dif 1 (50.65 KiB) Viewed 19 times

6. Refer to question 2. How many nails should be sampled from each machine if a 95% confidence interval for the true difference in proportions is to have a width of 0.1? Assume that samples of equal sizes are taken from each machine. 7. A scientist wishes to determine what volume of alkaline solution with given concentration is needed to neutralise a fixed volume of acid with specific concentration. Four values were observed when the titration was performed. Given in milli-litres the volumes were found to be 25.8, 25.5, 26.3 and 25.6. Obtain the 95% confidence interval for the volume of alkaline solution that will neutralise the acid. 8. The examination marks for Introductory Statistics is to be compared for students doing BSc Applied Statistics and students doing BSc Applied Science. Five students were selected from among the Statistics students and thirty five from among the Science students. The mean mark for the Statistics students was 72 with a standard deviation of 8.4 for the sample. The mean exam mark for the Science students was 65 with a standard deviation of 6.8 for the sample. Construct a 95% confidence interval for the difference in average Introductory Statistics marks for BSc Applied Statistics and BSc Applied Science students. 9. An experiment is replicated to determine the variation in temperature for which a certain process takes place. Six readings were obtained and recorded in units of Kelvin. The readings recorded were 371.5, 370.3, 370.6, 371.2, 370.8 and 369.2. (i) Construct a 95% confidence interval for the true variance in temperatures. (ii) As a result obtain a 95% confidence interval for the true standard deviations in temperatures. 10. Suppose independent samples of sizes n, and n, are from two normally distributed populations with variances and respectively. If Sand S denote the respective sample variances then (n-1)/o and (n.-1)/chave chi-square distribution with n-1 and n, -1 degrees of freedom respectively. These chi-square random variables are independently distributed since the samples are independently selected. (i) Construct a random variable having an F distribution with n, -Inumerator and 9,-l denominator degrees of freedom. (ii) Use the F-distribution to form a pivotal quantity and derive a 100(1-a)% confidence interval for 0/0