125 lines
3.4 KiB
Markdown
125 lines
3.4 KiB
Markdown
# Freelancer Rates
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Welcome to Freelancer Rates on Exercism's Elixir Track.
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If you need help running the tests or submitting your code, check out `HELP.md`.
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If you get stuck on the exercise, check out `HINTS.md`, but try and solve it without using those first :)
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## Introduction
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## Integers
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There are two different kinds of numbers in Elixir - integers and floats.
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Integers are whole numbers.
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```elixir
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integer = 3
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# => 3
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```
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## Floating Point Numbers
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Floats are numbers with one or more digits behind the decimal separator. They use the 64-bit double precision floating-point format.
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```elixir
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float = 3.45
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# => 3.45
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```
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### Working with numbers
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In the [`Integer`][integer-functions] and [`Float`][float-functions] modules you can find some useful functions for working with those types. Basic arithmetic operators are defined in the [`Kernel`][kernel-arithmetic-operators] module.
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### Conversion
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Integers and floats can be mixed together in a single arithmetic expression. Using a float in an expression ensures the result will be a float too.
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```elixir
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2 * 3
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# => 6
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2 * 3.0
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# => 6.0
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```
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However, when doing division, the result will always be a float, even if only integers are used.
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```elixir
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6 / 2
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# => 3.0
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```
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To convert a float to an integer, you can discard the decimal part with [`trunc/1`][trunc-1].
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[integer-functions]: https://hexdocs.pm/elixir/Integer.html#functions
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[float-functions]: https://hexdocs.pm/elixir/Float.html#functions
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[kernel-arithmetic-operators]: https://hexdocs.pm/elixir/Kernel.html#*/2
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[trunc-1]: https://hexdocs.pm/elixir/Kernel.html#trunc/1
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## Instructions
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In this exercise you'll be writing code to help a freelancer communicate with a project manager by providing a few utilities to quickly calculate daily and
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monthly rates, optionally with a given discount.
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We first establish a few rules between the freelancer and the project manager:
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- The daily rate is 8 times the hourly rate.
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- A month has 22 billable days.
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Sometimes, the freelancer is offering to apply a discount on their daily rate (for example for their most loyal customers or for non-for-profit customers).
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Discounts are modeled as fractional numbers representing percentage, for example `25.0` (25%).
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## 1. Calculate the daily rate given an hourly rate
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Implement a function to calculate the daily rate given an hourly rate:
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```elixir
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FreelancerRates.daily_rate(60)
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# => 480.0
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```
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The returned daily rate should be a float.
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## 2. Calculate a discounted price
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Implement a function to calculate the price after a discount.
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```elixir
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FreelancerRates.apply_discount(150, 10)
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# => 135.0
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```
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The returned value should always be a float, not rounded in any way.
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## 3. Calculate the monthly rate, given an hourly rate and a discount
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Implement a function to calculate the monthly rate, and apply a discount:
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```elixir
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FreelancerRates.monthly_rate(77, 10.5)
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# => 12130
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```
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The returned monthly rate should be rounded up (take the ceiling) to the nearest integer.
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## 4. Calculate the number of workdays given a budget, hourly rate and discount
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Implement a function that takes a budget, an hourly rate, and a discount, and calculates how many days of work that covers.
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```elixir
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FreelancerRates.days_in_budget(20000, 80, 11.0)
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# => 35.1
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```
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The returned number of days should be rounded down (take the floor) to one decimal place.
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## Source
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### Created by
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- @angelikatyborska
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### Contributed to by
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- @neenjaw |