1. In a sample 49 Canadians, proportion of people who have income less than$20000 is 0.24. What is the 95% confidence interval for the population proportion. In other words, what is the proportion of Canadians who have income less than$20000.
2. In a sample of 36 Canadian children, I find the average IQ level to be 138 and standard deviation 10. Find 95% confidence interval for population mean.
3. A simple random sample of 49 accounts is taken from an account receivables portfolio of XYZ Ltd and the average account balance is$630. The population standard deviationis known to be$60. Test the hypothesis that the population mean account balance is greater than$620 at= 0.05
4. In a recent satisfaction survey of 400 customers at XYC inc., it is found that proportion of customers who are completely satisfied is 0.28. Test the hypothesis that the proportion of customers who are completely satisfied is different from 0.26 at 0.05 level of significance.