# im stuck! this is 1 hard questionWatch

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#1
a liquid bottle states a nominal volume of 100ml.
measurements i have taken on modelling liquid volume is going into the bottles indicate a mean of 100ml and standard deviation is 0.2ml.
what amount of liquid should be dispensed to limit the risk of underfill to 1 in 40?

any ideas? thats the entire question, nothing before nor after.
0
11 years ago
#2
Let X ~ N(μ, 0.2²). Find μ such that P(X < 100) < 1/40.
0
11 years ago
#3
let x= the square root of lambda.
then you have to differeniate and then find the intercepts.
this way you will get the answer
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11 years ago
#4
(Original post by Zhen Lin)
Let X ~ N(μ, 0.2²).
I'm not disputing this and it is what I'd do in an exam, but why is it normally distributed?
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11 years ago
#5
Hmm. We don't know that it is. A χ²-test is needed.
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11 years ago
#6
Just assume it is, for random errors (like this) it'll pretty much always be the case (either intrinsically or as a result of CLT, etc)
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