Statisticians use the concept of mean and standard deviation to describe a collection of data. The mean is the average value of the items, and the standard deviation measures the spread of dispersal of the numbers about the mean. Formally, if X$1,$ X$2,$ X$3,..$Xn is a collection of data then:mean and standard deviationA college professor would like to use the curving method to assign grades to his course. Using Java $8$ streams and lambda functions, implement code to do the following:A standalone Java class called GradeAnalyzer has methods to read a set of grades into an internal relevant data structure from a flat file.Has a public method that enables the user of this class to calculate: $($i$)$ mean $($m$)($ii$)$ standard deviation $($s$)$ of the exam scores using Java $8$ Streams this approach must be used to get credit.A public method that enables the user to assign letter grades to each exam score $($ES$),$ as follows: ES $>$ m $+1\mathrm{.}5$s A m $+\mathrm{.}5$s $<$ ES $<$ m $+1\mathrm{.}5$s B m $-\mathrm{.}5$s $<$ ES $<$ m $+\mathrm{.}5$s C m $-1\mathrm{.}5$s ES $<$ m $-\mathrm{.}5$s D ES $<$ m $1\mathrm{.}5$s F For example, if m were $70$ and s were $12,$ then grades of $88$ or above would receive As$,$ grades between $76$ and $87$ would receive Bs$,$ and so on$.$