Ruby script to display grades of a student using hashes

class Student
	attr_accessor :firstname, :lastname
	attr_accessor :lgrade, :agrade
	
	def initialize(fname, lname)  
		@firstname = fname  
		@lastname = lname  
		@grades = Array.new
	end 

	def calcAverage
		sum = 0

		if @grades.size > 0
			@grades.each { |g| sum += g } 
			@agrade = sum / @grades.size
		else
			@agrade = 0
		end
		
		setLetterGrade
	end

	def addGrade(score)
		
		if score.is_a?(Integer) || score.is_a?(Float)
			@grades.push(score)
			calcAverage
		end
	end
	
	def setLetterGrade
		if @agrade >= 90.0
			@lgrade = "E"
		elsif @agrade >= 80.0
			@lgrade = "A"
		elsif @agrade >= 70.0
			@lgrade = "B"
		elsif @agrade >= 60.0
			@lgrade = "C"
                elsif @agrade >= 50.0
			@lgrade = "D"
		else
			@lgrade = "F"
		end
	
	end
end

def findClassAverage(studentsArray)
	classSum = 0.0
	studentsArray.each { |student| classSum += student.agrade }
	if studentsArray.size > 0 
		return classSum / studentsArray.size
	end
	
	return 0
end 

student1 = Student.new("John","Smith")
student1.addGrade(80)
student1.addGrade(100.0)
student1.addGrade(54.0)

student2 = Student.new("Mary","Johnson")
student2.addGrade(90.5)
student2.addGrade(90)
student2.addGrade(88.3)

classOfStudents = Array.new
classOfStudents[0] = student1
classOfStudents[1] = student2

classOfStudents.each { |student| puts "Student name: " + student.firstname + " " + student.lastname + " and their average was " + student.agrade.to_s + " " + student.lgrade }

puts "Class Average: " + findClassAverage(classOfStudents).to_s