1B. [43 Points] - MENDSTAT146.E.067. ASK YOUR TEACHER It is estimated that the mean life span of oilidrilling bits is 88 hours. Suppose an oil exploration company purchases drill bits that have a life span that is approximately normally distributed with a mean equal to 88 hours and a standard deviation equal to 1.2 hours. (Round your answers to four decimal places.) {a} what proportion of the company's drill blts will fail before ?3 hours of use? |:| (b) What proportion will last at least 73 hours? |:| (c) What proportion will have to be replaced after more than 103 hours of use? |:| You may need to use the appropriate appendix table or technology to answer this question. 19. [43 Points] - MENDSTAT146.E.087. ASK YOUR TEACHER Suppose that the IRS assigns audlting rates per state by randomly selecting 50 auditing percentages from a normal distribution with a mean equal to 1.65% and a standard deviation of 0.35%. (a) What is the probability that a particular state would have more than 2% of its tax returns audited? [Round your answer to four decimal places.) |:| (b) What is the expected value of x, the number of states that will have more than 2% oftheir income tax returns audited? (Round your answer to three decimal places.) |:| (c) Is it likely that as many as 16 of the 50 states will have more than 2% of their income tax returns audited? 0 Because X = 1.6 has a z-score less than 2, it is likely that as many as 16 of the 50 states will have more than 2% of their income tax returns audited. 0 Because X = 1.6 has a z-score of at least 2, it is unlikely that as many as 16 ofthe 50 states will have more than 2% of their income tax returns audited. 0 Because x = 16 has a zscore of at least 2, it is likely that as many as 15 of the 50 states will have more than 2% of their income tax returns audited. 0 Because x = 16 has a zscore less than 2, it is unlikely that as many as 15 of the 50 states will have more than 2% of their income tax returns audited. You may need to use the appropriate appendix table or technology to answer this