Tin has long been used in alloys with lead as solder, in amounts 5 to 70% w/w. Tin with lead forms a eutectic mixture at the weight proportion of 61.9% tin and 38.1% lead (the atomic proportion: 73.9%
The first quartile (Q 1) is defined as the middle number between the smallest number and the median of the data set.
Quartiles are a useful measure of spread because they are much less affected by outliers or a skewed data set than the equivalent measures of mean and standard deviation. For this reason, quartiles are often reported along with the median as the best choice of measure of spread and central tendency, respectively, when dealing with skewed and/or data with outliers. A common way of expressing quartiles is as an interquartile range.