Finding Probability… - QuestionCove
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