In 2014, the variance of the ages of all workers at a large company that has more than 30,000 workers was 133. A recent random sample of 25 workers selected from this company showed that the variance of their ages is 112.
a. Using a 2.5% significance level, can you conclude that the current variance of the ages of workers at this company is lower than 133? Assume that the ages of all current workers at this company are (approximately) normally distributed.
b. Construct a 98% confidence intervals for the variance and the standard deviation of the ages of all current workers at this company.