Probability help!A certain type of thermal battery for an airplane navigation device backup power has a mean?
Katie asked:
A certain type of thermal battery for an airplane navigation device backup power has a mean life of 300 hours with a standard deviation of 15 hours. What proportion of these batteries can be expected to have lives of 322 hours or less? Assume a normal distribution of backup power device lives.
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A certain type of thermal battery for an airplane navigation device backup power has a mean life of 300 hours with a standard deviation of 15 hours. What proportion of these batteries can be expected to have lives of 322 hours or less? Assume a normal distribution of backup power device lives.
May 18th, 2009 at 4:56 am
P(X < 322.0) = P((x - 300) / 15.0) < (322.0 - 300) / 15.0) = P(Z < 1.47) = 0.9288