Bummer! This is just a preview. You need to be signed in with a Basic account to view the entire video.

Preview

Start a free Basic trial
to watch this video

Sign up for Treehouse

Introducing the Practice

2:19 with Jay McGavren

Let's practice some basic Ruby to make sure that everything you've learned so far sticks. We'll review numeric types such as Fixnum and Float, as well as math operations.

These videos cover the concepts you'll need to complete the exercise:

To complete the extra credit, you'll need:

  • 0:00

    [MUSIC]

  • 0:04

    Let's practice some basic Ruby to make sure that everything you've learned so

  • 0:08

    far sticks.

  • 0:09

    We'll review numeric types such as fix, num and float, as well as math operations.

  • 0:14

    We're gonna ask you to build a simple Ruby program that calculates the average of

  • 0:18

    some numbers.

  • 0:19

    I've attached a work space to this video which includes an average .rb

  • 0:23

    starter file, with instructions as Ruby comments.

  • 0:26

    You should open the work space now.

  • 0:29

    If you have Ruby installed on your computer you can choose file,

  • 0:32

    download work space.

  • 0:33

    And that will download all the files to your

  • 0:38

    computer where you can edit and run them.

  • 0:40

    Or you can just set it and run everything in the work space.

  • 0:44

    Write your code in the average.rb file and save your work.

  • 0:47

    Then switch to the terminal and type ruby average.rb to run your program.

  • 0:53

    Up here at the top of the file we've already defined four Ruby

  • 0:56

    variables for you.

  • 0:57

    Your job is to take the value of all those variables and

  • 1:00

    calculate the average, that is the mean of them.

  • 1:03

    You can do this by adding all their values together and

  • 1:06

    then dividing by the number of values, that's four values in this case.

  • 1:11

    Now there's a little catch to this, for the numbers 12, 7, 5 and 10,

  • 1:14

    you should get an average of 8.5, not 8.

  • 1:18

    If you find that you got the number of 8 even,

  • 1:21

    it's probably because you divided by a fixed sum, an integer.

  • 1:24

    So make sure that you're dividing by a float instead.

  • 1:27

    See the teacher's notes for

  • 1:29

    videos that can help you fix this problem if it arises.

  • 1:33

    There's an extra credit problem down here at the bottom you can try.

  • 1:35

    You can prompt the user for some values to average by populating the E, B, C and

  • 1:40

    D variables by calling the get s method.

  • 1:44

    Note however, that the get s method returns the string not a number.

  • 1:47

    So you'll need to call the to_f method on the value

  • 1:50

    returned by gets to convert it to a float.

  • 1:53

    That is when we type gets.to_f and then store that value in a variable.

  • 1:59

    Then you can calculate an average of all the variables as you did previously.

  • 2:03

    I've linked to some videos in the teacher's notes which you can refer to

  • 2:07

    if you get stuck.

  • 2:09

    After you've written your program you can proceed to the next video

  • 2:11

    where you can compare my solution to yours.

  • 2:14

    Ready?

  • 2:15

    Get started on your program.

  • 2:16

    I'll show you my version and the next video.

You need to sign up for Treehouse in order to download course files.

Sign up