How much population falls between median and median plus one standard deviation in a normal distribution ?
(A) 0.34 (B) 0.68 (C) 0.17 (D) 0.47
(A) NORMAL DISTRIBUTION

Shape is bilaterally symmetrical
Mean = Median = Mode (coincide)
50% of all values lie above Mean (or Median or Mode)
Mean + 1SD cover 68% values (Mean + 1SD cover 34% values)
Mean + 2SD cover 95% values (Mean + 2SD cover 47.5% values)
Mean + 3SD cover 99% values (Mean + 3SD cover 49.5% values)