The lifetime of a certain brand of electric light bulb is known to have a standard deviation of 52 hours. Suppose that a random sample of 80 bulbs of this brand has a mean lifetime of 500 hours. Find a 90% confidence interval for the true mean lifetime of all light bulbs of this brand. Then give its lower limit and upper limit. Carry your intermediate computations to at least three decimal places. Round your answers to one decimal place. (If necessary, consult a list of formulas.) Lower limit: X ? Upper limit:A random sample of 200 adults was given an IQ test. It was found that 114 of them scored higher than 100. Based on this, compute a 99% confidence Interval for the proportion of all adults whose IQ score is greater than 100. Then find the lower limit and upper limit of the 99% confidence interval. Carry your intermediate computations to at least three decimal places. Round your answers to two decimal places. (If necessary, consult a list of formulas.) Lower limit: X ? Upper limit