Originally Posted by

**peanutbutter** I have a 3 part question and I am fairly confident I have the correct final answer. It goes

A region's population is 7,800 and it's per capita income approximately observes a normal distribution with the mean being $12,100 and the standard deviation being $6,050. Suppose $5,500 is the poverty line. What percent of people in the region live under the poverty line?

So I have

Z=X-mean/ std

Z=5500-12100 / 6050 = - 1.09

P(-1.09 < Z < 0) = P(0<Z<1.09)= 0.3621

0.50- 0. 3621 = 0.1379

7800 * 0.1379 = 1075.62

That's what I have. The thing is, since I am wanting to get a good grade on this from my professor, I am worried I have left out some notations maybe? I mean, I think I have the right answer and everything, but have I "shortcutted" anything, is the process from z-score to final answer as simple as 5 lines? I just want everything to be perfect. I found the z-score, then I expressed a probability...did I do the probability expression right? BTW, my normal table in my book is from 0 to Z to the right of the mean. (I have been posting questions sometimes on Yahoo answers, and people ask me where I am getting my probabilities wrong, as if the table in my book is wrong. I don't know how that could be)

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