gistfile1.rb

def average_time_of_day(times)
  times.map! {|time| time.scan(/(\d+):(\d{2})(\w{2})/)}.
        map! {|l| l[0].first(2).map(&:to_i) << (l[0].last == 'pm')}
  seconds = 0
  times.each { |t| seconds += t[0]*3600 + (12 if t[2]).to_i + t[1]*60 }
  average = seconds/times.size
  hours = average/3600
  hours, minutes, ampm = hours-(12 if hours>12).to_i, (average- hours*3600)/60,
      hours>12 ? 'pm' : 'am'
  "#{hours}:#{minutes}#{ampm}"
end