Peter is shopping for an air conditioner.

1. (a)

   Peter writes down the duration he would use the air conditioner in the following table.

   Show that the mean length of time that she would use the air conditioner each day is 6 hours 45 minutes.

   Answer ...

   
2. (b)

   Peter is deciding between two models of air conditioner. Page 25 shows the information that he needs, including the electricity consumptions of the two models.

   Based on his usage, Peter estimates that the electricity consumptions in one year will be 1755 kWh for Model S and 1066.5 kWh for Model E.

   Show with workings how he come up with these estimates.

3. (c)

   The total cost of an air conditioner includes its price, the cost of the electricity it consumes and the cost of servicing it.

   Electricity costs 25.3 cents per kWh, including GST.

   Peter would like the air conditioner to be serviced once every 4 months.

   Based on his usage, which model should he choose if he intends to use the air conditioner for 7 years?

   Justify your decision with calculations.

   (You should assume that the costs of electricity and servicing remain the same.)