Problem Set 5: Water Meter

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Task Outline

Due Date: Wednesday, October 16, 2019
Total Points: 10
Implement a Python program that calculates the amount of money that a customer will be billed, based on their water usage.

A water utility is responsible for supplying clean, fresh water to its customers in a given geographical area.
The water utility will typically charge different rates for each category of customer. Supplying water to individual households is relatively straightforward, so they are charged minimal rates. However, commercial and industrial factories may require massive amounts of water, so they are charged more for the necessary supporting infrastructure.
A customer's water bill depends on how many gallons of water they consumed during a particular billing period.
A water meter is used to determine a customer's water consumption. It consists of a dial that has nine digits. However, note that the final digit in the dial records one-tenth of a gallon.
In other words, if the water meter reads 923874345 then this corresponds to 92387434.5 gallons.
The water meter is read once at the beginning of the billing period, and then once and the end. A customer's water consumption, in gallons, is computed from the difference in these two meter readings.

There are three categories of customer: residential, commercial, and industrial. The following is the fee schedule for each of these categories:

A base rate $1000.00 for 40000 gallons or less, plus $0.00025 for each additional gallon used.

A base rate of $1000.00 for 40000 gallons or less. A base rate of $2000.00 if usage exceeds 40000 gallons, but does not exceed 80000 gallons. A base rate of $3000.00 plus $0.00025 for each additional gallon if usage exceeds 80000 gallons.

Note that the meter's dial has nine digits and records the tenths of a gallon. For example, if the beginning reading was 444400003 and the ending reading was 444400135, then the customer used 13.2 gallons of water during that billing period.
We won't consider the case where the water meter "flips over" from 999999999 to 000000000.

Description	File Size	File Name
`Python` Source Code for Water Meter	1.4KB	pset05.zip

Contents of pset05.zip:

PSet05WaterMeter/
├── testwaterbilling.py
└── waterbilling.py

Write a Python program in the file watermeter.py that determines the amount of money that a customer must pay for their water usage during a particular billing period.
You will write your solution in a function called calculatebill(customer, begin, end) right below the place where it says: YOUR CODE HERE
When the function call calculatebill("residential", 444400003, 444400135) is executed, the output of the program should be: 5.0066

Run the file testwatermeter.py to execute the PyUnit test bench. PyUnit indicates a successful test with an OK output, and an unsuccessful test with a FAIL output.