Computer Science · Oct / Nov 2018 · Paper 2 SL · Question 4

4. A water authority supplies water to its customers. The amount of water supplied to each customer is measured by a meter. There are two types of meter; an old meter and a new meter. The water authority also provides sewage services. This is when waste water is returned from the customers’ houses to a central processing plant. Only the new meter is able to estimate the amount of waste water returned. The authority reads the meters annually and the charges for these services are sent to the customers. The annual charges to customers are calculated using a model that takes into account the following variables: METER_TYPE The type of meter which can be either old or new. WATER_IN The reading displayed on both meters (the reading is a 6-digit display in litres) which is used to measure the volume of water supplied. WATER_OUT The reading displayed on the new meter only (the reading gives a 6-digit integer display in litres) which is used in estimating the volume of waste water returned to the sewage system. INFRA_CHARGE The cost of maintaining the infrastructure for supplying water and providing the sewage service. This is an annual charge of $204.80. This amount is reduced by 10 % if a new meter is used.

Read automatically from the paper; the printed page above is exact.