Question

19. The life of mixers follows the normal probability distribution with a population mean of 60,000 hours and a population standard deviation of 1750 hours. Suppose you bought a mixer for yourself, your mother, your sister, and your brother. What is the likelihood the mean life of these four mixers is more than 58,000 hours? A. 0.1957 B. 0.9889 C 0.4352 D 0.0121

D is incorrect. Please show your work.

Answer 1

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het y be the mean life of four mixers which follows Normal Distributior. ic X~N 160,000, 1750) where, u=60,000 hrs, o= 17.50 hrs. We know, z = x- ~N(0,2) P(x> 58000) = 1 - P(XS 58000) = 1 - PC Horsens 58000 - 10,000) - 1-P (Żs - 1-14) - 1- (-1-14) 31-1+ (1:14) = 0.8729 (from standard Normal Table) The nearest correst answer is B70.9889 1750