Nicole missed the lesson on normal distribution and needs to do her homework. Explain to Nicole how to use the mean and standard deviation of a normal distribution to determine the top 5% of the population.

Question

anonymous · Answer

what's your question?

anonymous · Answer

That is the question! ^^^

anonymous · Answer

do you understand what the normal distribution is and how it "works"?

anonymous · Answer

I think so!

anonymous · Answer

I feel like for this question I'll have to use the z-score? No?

anonymous · Answer

yes, of course.

$$z=\frac{ x-\mu }{ \sigma } \Rightarrow x=\mu +z\cdot \sigma$$

you'd have to use the standard normal table to find the z-score corresponding to the top 5% and use that along with the mean and std dev of the population data.

anonymous · Answer

okay, so how would I go about completing this question then? I am still lost

anonymous · Answer

does your class use a normal table?

anonymous · Answer

Yes

anonymous · Answer

how does the table work?  does it give tail probabilities P(X>z), cumulative probabilities P(X<z) or probabilities from the mean to the z-score |P(X<z)-.5|?

mathmale · Answer

Look at this graph of a "normal distribution:"|dw:1406142709636:dw|