list_statistics.rb

list = [75, 100, 85, 65, 84, 87, 95]

def highest(list_given)
  maximum = 0
  list_given.each do |item|
    if item > maximum
      maximum = item
    end
  end
  return maximum
end

def lowest(list_given)
  minimum = list_given[0]
  list_given.each do |item|
    if item < minimum
      minimum = item
    end
  end
  return minimum
end

def add_up_list(list_given)
  total = 0
  list_given.each do |item|
    total += item
  end
  total
end

def list_size(list_given)
  size = 0
  list_given.each do |item|
    size += 1
  end
  size
end

def average(sum, list_given_size)
  sum / list_given_size
end

puts "Highest: #{highest(list)}"
puts "Lowest: #{lowest(list)}"
puts "Average: #{average(add_up_list(list), list_size(list))}"

I think gists add whitespace? I have all the Sublime Text settings, and when I open up the file in Sublime there's no whitespace. But thanks for all the feedback!