OpenStudy (anonymous):

Finding Probability Using a Normal Distribution The weights of newborn baby boys born at a local hospital are believed to have a normal distribution with a mean weight of 3537 grams and a variance of 285,156. If a newborn baby boy born at the local hospital is randomly selected, find the probability that the weight will be less than 4172 grams. Round your answer to four decimal places.

2 years ago
OpenStudy (anonymous):

Been a while since I took stat, but I think this is a z-score problem

2 years ago
OpenStudy (anonymous):

Yes it is i need help desperately

2 years ago
OpenStudy (lyrae):

Fundamental probability theory states: \[P_{\chi}(\chi \le x) = F_{\chi}(x)\]In this question \(\chi\) is distributed as a normal distribution with \(\mu = 3537\) and \(\sigma^2 = 285,156\). \(F_{\chi}(x)\) is the cumulative distribution function of \(\chi\), i.e. normalcdf.

2 years ago
OpenStudy (anonymous):

So how do i do it?

2 years ago
OpenStudy (anonymous):

So how do i do it?

2 years ago
OpenStudy (lyrae):

Use a statistical calculator, Excel, wolfram alpha, etc. and use the cumulative distribution function for normal distribution (normalcdf) with given values for parameters x, \(\mu\) \(\sigma\).

2 years ago
OpenStudy (anonymous):

I dont understand what u just said at all

2 years ago
OpenStudy (anonymous):

I dont understand what u just said at all

2 years ago
OpenStudy (anonymous):

How do i find the standard deviation?

2 years ago
OpenStudy (lyrae):

Use this: http://www.danielsoper.com/statcalc3/calc.aspx?id=53 Mean = \(\mu\) = 3537 Standard deviation = \(\sqrt{variance}\) = \(\sqrt{\sigma^2}\) = \(\sigma\) = \(\sqrt{285,156}\) x = 4172

2 years ago
OpenStudy (anonymous):

Im sorry i still dont understand. I dont get that calculator. There isnt a a place for me to put the variance in

2 years ago
OpenStudy (anonymous):

or is the variance the standard deviation?

2 years ago
OpenStudy (lyrae):

standard deviation = \(\sqrt{variance}\)

2 years ago