D Question 14 4 pts Use the confidence level and sample data to find a confidence interval for estimating the population . Round your answer to the same number of decimal places as the sample mean. A random sample of 70 light bulbs had a mean life of x = 471 hours with a standard deviation of a = 35 hours. Construct a 90% confidence interval for the mean life, u, of all light bulbs of this type. O 461 hr