An electric kettle used to prepare tea, takes 2 minutes to boil 4 cups of water (1 cup contains 200 cc of water) if the room temperature is `25^@ C`, (a) If the cost of power consumption is `Re 1.00` per unit `(1 unit = 1000 watt-hour)`, calculate the cost of boiling 4 cups of water. (b) What will be the correspoinding cost if the room temprature drops to `5^@ C`?