Posted by Mary on Sunday, March 7, 2010 at 2:41pm.
Bank of Connecticut estimated that balance on credit cards have
follows Normal Distribution mean $845 with standard deviation $270.
Calculate probability that balance on a single credit card is greater than $750

Statistics  drwls, Sunday, March 7, 2010 at 3:35pm
Try using
http://psych.colorado.edu/~mcclella/java/normal/accurateNormal.html
or a table of the error function.
The answer is 63.8%