Scores on a test have a mean of 64 and Q3 is 82....(cont in details)?

Question

Scores on a test have a mean of 64 and Q3 is 82. The scores have a distribution that is approx norm. Find the standard deviation.

Answer 1

about 34.1 % of 64 is the standard deviation
look for instance at http://en.wikipedia.org/wiki/Image:Standard_deviation_diagram.png

it doesnt matter that Q3=82
what matters is that the mean = 64 ( mu )
and that u are dealing with a normal distribution