time_sheet.rb

require 'spreadsheet'
Spreadsheet.client_encoding = 'UTF-8'

class TimeSheet
  def calculate_total_working_hours
    employeeHash = {}

    book = Spreadsheet.open 'timesheet.xls'
    default_sheet = book.worksheet 0  # If there are multiple worksheet it will take the 1rst.

    default_sheet.each 1 do |row|     # This will start from the 1st record.
      employeeHash[row[0]] = employeeHash.has_key?(row[0]) ? employeeHash[row[0]] + row[1] : row[1]
    end

    puts "Timesheet entry***** #{employeeHash.inspect}"
  end
end

time_sheet = TimeSheet.new
time_sheet.calculate_total_working_hours