A certain characteristic in a large population has a distribution that is symmetric about the mean m. If 66 percent of the distribution lies within one standard deviation d of the mean, what percent of the distribution is less than m + d ?	Choose the correct option:
A) 16%  B) 32%  C) 83%  D) 84%  E) 92%
This is easiest to solve with a bell-curve histogram. m here is equal to µ in the Gaussian normal distribution and thus m = 50% of the total population.   So, if 66% is one st.Dev, then on either side of m we have  66/2= 
<gadget id="calculator"> 66/2</gadget>
<output>33</output>
33%. So, 33% are to the right and left of m (= 50%). In other words, our value m + d = 50 + 33= 
<gadget id="calculator">50 + 33</gadget>
<output>83</output>
83% goingfrom the mean m, to the right of the distributionin the bell shaped histogram.. This means that 83% of the values are below m + d.   Like I said, doing it on a bell-curve histogram is much easier to fullygethow this works, or you could apply GMAT percentile jargon/theory to it   83%
<result>C</result>
A certain characteristic in a large population has a distribution that is symmetric about the mean m. If 66 percent of the distribution lies within one standard deviation d of the mean, what percent of the distribution is less than m + d ?