# coding: utf-8
grades = [100,100,90,40,80,100,85,70,90,65,90,85,50.5]

def printGrades(grades):
	for grade in grades:
		print grade

def gradesSum(grades):
	total = 0
	for grade in grades:
		total += grade
	return total

def gradesAverage(grades):
	sum_of_grades = gradesSum(grades)
	average = sum_of_grades / float(len(grades))
	return average

def gradesVariance(scores):
	average = gradesAverage(scores)
	variance = 0
	for score in scores:
		variance += (average - score) ** 2
	return variance / float(len(scores))

def gradesStdDeviation(variance):
	return variance ** 0.5

printGrades(grades)
print "%.2f" % gradesSum(grades)
print "%.2f" % gradesAverage(grades)
print "%.2f" % gradesVariance(grades)
variance = gradesVariance(grades)
print "%.2f" % gradesStdDeviation(variance)