statistics
posted by Ronnie .
A maker has the opportunity to purchase several acres of land that is divided up into several lots for building singlefamily homes.
It is known that the average sale price of all of the lots is $80,000 and the standard deviation of the sale price is $12,000. What can you say about the percentage of lots that have selling prices between $56,000 and $104,000?
Choose one answer.
a)at most 25% of the selling prices lie in this interval
b.) at least 75% of the selling prices lie in this interval
c) approximately 99.7% of the selling prices lie in this interval
d) none of these

Here is a neat little applet that let's you do these kind of questions without even finding the zscores first.
http://davidmlane.com/hyperstat/z_table.html
just enter 80000 as the mean, 12000 as the standard deviation, click on the "between" button and enter the range from your question.
I got .9545 or 95.5%