SOLUTION: If the mean income of plumbers is $3000 a month, the standard deviation is $300, what per cent of plumbers make more than $3300? (roughly)

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Question 253082: If the mean income of plumbers is $3000 a month, the standard deviation is $300, what per cent of plumbers make more than $3300? (roughly)
Answer by hokies(65) About Me  (Show Source):
You can put this solution on YOUR website!
Assume a standard distribution.
Use a z-table. One is located at: http://www.easyhomeworkhelp.com/statistics/ztable.jpg
+1 standard deviation is the same as a z-score of 1.0. From the table, it has a z-score = .8413. Therefore, 84.13% of plumbers make less than $3300, and 1-.8413=.1587, or 15.87% of plumbers make more than $3300.
Hope this helps! :-)