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Suppose that the functional life of a certain brand of CD-player is normally distributed with average life u=28 months with a standard deviation of 0:5 months. The CD company refunds the money back to its customer if a CD becomes defective within the guarantee period 2 years after the purchase. Set a random variable X represent the life of a CD-player in months. a. [5 points] What is the probability that a defective CD-player will be refunded? (In other words, what percentage of the total production of CD-player should the company expect to refund?) b. [5 points] If the CD company does not want to make refunds on more than 12% of the CD-player it makes, how long should the guarantee period he (to the nearest month)? [ Hint: For this problem 2( b), you need to apply the Inverse normal distribution.) a. [5 points] Suppose that the time to complete a b. [ 5 points] test is normally distributed with mean 11:48 Find 2 value so that 94% of stande minutes and standard deviation a=6 minutes. normal curve lies between -z and 2. After how many minutes, can we expect just about 4% of the tests remain to be completed