A survey found that people keep their televisions an average of 4.8 years. The standard deviation is 0.79 year. If a person decides to buy a new TV, find the probability that he or she owned the old one for more than 2.9 years. Assume the random variable is normally distributed.
so 2.9 years we must first find how many S.D. away from 4.8 that is so .79 is one S.D. so what we do is 4.8-2.9 all divided by .79 = 2.405 S.D. away so now we look in our table for something that is -2.41 since we round up so .008 now we are looking for the probability that its more than 2.9 years so 1-.008 and that gives .992 which means the probability that someone owns a tv for more than 2.9 years is 99.2%
May 30th, 2015
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