An electric iron of rating 1800W is used for 1h daily throughout a 31-day month. It is replaced by an energy-efficient model rated at 1200W, which is used for the same duration each day.
(i) For each iron, calculate the monthly electrical energy consumed in kWh.
(ii) The tariff is ₹5.50 per unit. Find the monthly cost of operating each iron and hence the monthly saving obtained by using the efficient model.
(iii) Express the energy saving in joule for the month.