The price of a first class postage stamp was raised from 37 cents to 39 cents on Jan. 8, 2006. The change followed the approval of a Postal Rate Commission recommendation to raise prices on all classes of mail approximately 5.4 percent.
The interquartile range (IQR) is a measure of variability, based on dividing a data set into quartiles. Quartiles divide a rank-ordered data set into four equal parts.he interquartile range (IQR) is a measure of variability, based on dividing a data set into quartiles. Quartiles divide a rank-ordered data set into four equal parts.
The IQR (the width of an interval which contains the middle 50% of the data set) is normally computed by subtracting the first quartile from the third quartile. In a normal distribution (with mean 0 and standard deviation 1), the first and third quartiles are located at -0.67448 and +0.67448 respectively.he IQR (the width of an interval which contains the middle 50% of the data set) is normally computed by subtracting the first quartile from the third quartile. In a normal distribution (with mean 0 and standard deviation 1), the first and third quartiles are located at -0.67448 and +0.67448 respectively.