Question 833116: The shelf life of a battery produced by one major company is known to be normally distributed, with a mean life of 3.5 years and a standard deviation of 0.75 years. What range of years contains 68% of all battery shelf lives?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! The shelf life of a battery produced by one major company is known to be normally distributed,
with a mean life of 3.5 years and a standard deviation of 0.75 years. What range of years contains 68% of all battery shelf lives?
-----
If you are using Chebechev's approximations that interval
would be 1 std to the left of the mean to 1 std to the right of the mean.
------
Ans: 3.5-0.75 to 3.5+0.75 = (2.75,4.25)
------
If you are using z-scores:
0.5-0.34 = 0.16
z = invNorm(0.16) = -0.9945
x = 3.5-0.9945*0.75 = 2.7542
-----
Ans: (2.7542,4.2542)
======================
Cheers,
Stan H.
=================
|
|
|
