Module 4 Statistics (Questions and Answers A+ Graded 100% Verified)

Module 4 Statistics (Questions and Answers A+ Graded 100% Verified) To find critical value, when do you use the T table instead of Z? Ans: When the population variance is unknown but sample variance is known Alpha=20% the confidence interval for mu is found to be (110, 321). Which of the following statement(s) is true? Ans: (b) We are 20% sure that the actual mean is outside the range of 110 to 321. (d) We are 80% sure that the actual mean is between 110 to 321. Which of the following statements is correct? Ans: Point estimate of population mean is sample mean How large a sample is necessary if we wish to estimate 95% confidence interval which is accurate within 25% and population standard deviation is known to be 2 years. Ans: 246 For the 95% confidence interval of mean sample size is 9 (sigma unknown). what is t-alpha over 2 (Critical value)? Ans: 2.306 For 5 degrees of freedom and 95% confidence level what are the two critical values (Chi-Square_(1-alpha/2) and Chi-Square_(alpha/2)) from chi-square table? Ans: Chi-Square_(1-alpha/2)=0.831 Chi-Square_(alpha/2) =12.833 A company is interested on average wages of employee and variance. A sample of 20 workers is taken and it is found that mean wage was $9.5 and sample standard deviation was. $1.30. Construct a 95% confidence interval for the population variance. Ans: (0.977, 3.605) A random sample of 250 families in City A revealed that 65 families had annual income over $100,000. Another random sample of 300 family from city B contained 45 families had annual income over $100,000. Find the point estimate of the difference of proportion between City A and City B. Ans: 0.11 Bowling league members bowled at two different locations. At the location with oiled lane a sample of 35 bowling has mean score 205.5 and sample standard deviation 25.4. on the other hand, at the location with dry lanes, a sample of 35 bowling has mean score 185.0 and sample standard deviation is 18.4. Find pooled variance. Ans: 491.86