All are true regarding Normal distribution curve except

NORMAL DISTRIBUTION The normal distribution or 'normal curve' is an impoant concept in statistical theory. Let us suppose, we collect the haemoglobin values of a very large number of people and make a frequency distribution with narrow class intervals, we are likely to get a smooth, symmetrical curve. Such a curve is called a normal distribution or normal curve. The shape of the curve will depend upon the mean and standard detion which in turn will depend upon the number and nature of observations. It follows, therefore, there will be an infinite number of normal curves. Standard normal curve Although there is an infinite number of normal curves depending upon the mean and standard detion, there is only one standardized normal curve, which has been devised by statisticians to estimate easily the area under the normal curve, between any two ordinates. The standard normal curve is a smooth, bell-shaped, perfectly symmetrical curve, based on an infinitely large number of observations. The total area of the curve is 1; its mean is zero; and its standard detion is 1. The mean, median and mode all coincide. The distance of a value (x) from the mean (X) of the curve in units of standard detion is called "relative dete or standard normal variate" and is usually denoted by Z. Ref : Park 23rd edition Pgno : 849