Question

The distribution of age of 1000 persons is normal. The mean of the distribution is 32 years and the
standard deviation is 8 years
1) Find the maximum age of a person coming from 20 % of persons having least age.
2) Find the minimum age of a person among 120 persons having maximum age. (Ans. (1) 25 (2) 41]​

Answer 1

Answer:

The Empirical Rule is just an approximation and only works for certain values. What if you want to find the probability for x values that are not integer multiples of the standard deviation? The probability is the area under the curve. To find areas under the curve, you need calculus. Before technology, you needed to convert every x value to a standardized number, called the z-score or z-value or simply just z. The z-score is a measure of how many standard deviations an x value is from the mean. To convert from a normally distributed x value to a z-score, you use the following formula.