SOLUTION: The life time of a certain electrical part is normal random variable with mean life 100 hours and standard deviation 20 hours. If 16 such parts are tested, find the probability tha
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Question 918527: The life time of a certain electrical part is normal random variable with mean life 100 hours and standard deviation 20 hours. If 16 such parts are tested, find the probability that the sample mean is
a. Less than 104:
b. Between 98 and 104 hours.
Answer by ewatrrr(24785) (Show Source): You can put this solution on YOUR website!
a) z = 4/5, P(x <104) = P(z < 4/5) = normalcdf(-100, .8)
b) z = -2/5 and 4/5
P(98 < x < 104) = P(-.4 < z < .8) = normalcdf(-.4, .8)
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