1. ## Two stats problems

I have the key book but my answers aren't coming up the same so I know I am messing up somewhere. If you can help I'd be very thankful

a)
If the mean salary for high school teachers in the US is $29,835 and the standard deviation is$3000, find the probability that a teacher makes more than $35,000. So I first have to find the Z score, which would be = 35,000-29835 / 3000 Z= 1.72166 which = .4657 (around) after looking at a chart and to find the probability above 35,000, I had .5000 - .4657 = .0341 b) Houses in a certain neighborhood sell for an averae price of$126,000 with a standard deviation of $3,000. Find the Range for the middle 85% of houses in the neighborhood Ack I found what I did wrong. I misread it as 95% and treated it as a confidence interval problem. To find the correct answer, would I treat it as a Z score problem? 2. Originally Posted by aargh27 I have the key book but my answers aren't coming up the same so I know I am messing up somewhere. If you can help I'd be very thankful a) If the mean salary for high school teachers in the US is$29,835 and the standard deviation is $3000, find the probability that a teacher makes more than$35,000.

So I first have to find the Z score, which would be = 35,000-29835 / 3000

Z= 1.72166

which = .4657 (around) after looking at a chart

and to find the probability above 35,000, I had .5000 - .4657 = .0341
I don't know what table you are using but mine gives:

P(Z<=1.72) = 0.9573,

so:

P(Z>1.72) = 1-0.9573 = 0.0427

Also this is all invalid without a statement to the effect that the distribution
of salaries is normal, or that you are assuming it so.

RonL

3. My table isn't exact so I estimated... and no, there is no statement about the the sales being normal but I am pretty sure I am ment to assume it, yes.