Normal distribution curve is determined by:

Ans. a (Standard deviation and mean). (Ref. Park PSM 22nd/pg. 792)1. Normal distribution curve/ Standard normal curve/ Normal Gaussian curve# A smooth symmetrical curve.# Total area of the curve is 1; its mean is zero; and its standard deviation is 1.# The mean, median and mode all coincide.# Limits on either side of mean are called "confidence limits".- Area between one standard deviation on either side of the mean (x + 1 m) will include approximately 68% in the distribution.- The area between two SD on either side of the mean (x + 2 m) approximately 95 %.- Area between three SD on either side of mean (x + 3 m) approximately 99.7 % in the distribution.# Percentage of values in a population, which will fall within various ranges within an ideal curve of normal distribution:- Mean +/- d 68.27%- Mean +/- 1.96d 95.00%- Mean +/- 2d 95.45%- Mean+/-3d 99.73%2. Poisson distributionLimiting form of binominal distribution when probability of success is closer to zero and numbers of trials are infinite. Mean=variance.3. Skew distribution Skewed to left (negatively skewed);Skewed to Right (Positively skewed)1If more outlying values are smaller than the rest, data are said to be skewed to left;If more outlying values are larger than the rest, data are said to be skewed to left2Data have longer tail among lower values;Data have longer tail among higher values3Median>mean;Median<mean