The owner of the Stereo Company, offers 1-year warranties on all the stereos his company sells. For those 25 stereos that were serviced under the warranty last year, the average cost to fix a stereo was $65 and sample standard deviation was $15. Calculate 99 percent confidence interval for true standard deviation of the cost of repair. Sam has decided that unless the true standard deviation is less than $ 20 , he will buy his stereos from different retailer .Help owner, test the appropriate hypothesis, using a significance level of 0.01 . Should he switch retailers?