lestion 9 of 9 w Policies irrent Attempt in Progress Johnson Electronics Corporation makes electric tubes. It is known that the standard deviation of the lives of these tubes is 145 hours. The company's research department takes a sample of 90 such tubes and finds that the mean life of these tubes is 2100 hours, What is the probability that this sample mean is within 28 hours of the mean life of all tubes produced by this company? Round your answer to four decimal places. P eTextbook and Media