STA 406 Assignment No.1 Solution Ideas and Discussion Fall 2014

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Check Online Solution Ideas STA 406 Assignment No.1 and Discussion Fall 2014


Assignment # 1 (Lessons 1- 2)



Question 1: (Marks: 2+5=7)

a. Let U and V are two unbiased estimators of λ and Variance (U) ≤ Variance (V), then which estimator is more efficient and why?


b. A mobile company XYZ wants to conduct a survey to find the proportion P of those customers that are happy with the purchase of their new mobile phone. The company took a random sample of 1000 customers who recently purchased the new mobile phone. They found that among those, 400 customers were happy with their purchase. Find the 95% Confidence Interval for P?








Question 2: (Marks: 4+4=8)

a. An independent random sample of 50 and 70 animals from two farms show the average animal weight to be 50 kg and 40 kg with standard deviation of 2.5 kg and 1.5 kg respectively. Assuming normality, construct a 95% confidence interval for the expected difference in the weights.




b. The standard deviation of the lifetime of certain TV picture tubes is estimated as 150 hours. How much large a sample must be taken in order to be 99% confident that the error in the estimated means lifetime will not exceed 25 hours.