Warthogger
New member
- Joined
- Dec 2, 2013
- Messages
- 1
Normal distribution problem ( Gaussian )
Hi I've managed well so far but I've come across a problem I'm unaware how to apply the Z score to.
The problem is.
The Life of a machine component is normally distributed with mean 60 hours and standard deviation 30 minutes. If 2.5% of components last more than X1 hours, find the value of X1.
X = ? not sure how to work it out or how to rearrange the formula with out been given Z value or X
mu = 60
Std Dev = 30
So i did 2.5% as 0.5 - 0.025 to get the area remaining from 0 - Z1 which = .4975 and found that value on the z chart to find the value of Z.
I then used the formula x=Mu+(Z)(Sigma) and got
60+(2.8*30) = 144 so am i right in saying X = 144?
any advice would be appreciated.
Hi I've managed well so far but I've come across a problem I'm unaware how to apply the Z score to.
The problem is.
The Life of a machine component is normally distributed with mean 60 hours and standard deviation 30 minutes. If 2.5% of components last more than X1 hours, find the value of X1.
X = ? not sure how to work it out or how to rearrange the formula with out been given Z value or X
mu = 60
Std Dev = 30
So i did 2.5% as 0.5 - 0.025 to get the area remaining from 0 - Z1 which = .4975 and found that value on the z chart to find the value of Z.
I then used the formula x=Mu+(Z)(Sigma) and got
60+(2.8*30) = 144 so am i right in saying X = 144?
any advice would be appreciated.
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