Introducing the Practice

[MUSIC] 0:00 Let's practice some basic Ruby to make sure that everything you've learned so 0:04 far sticks. 0:08 We'll review numeric types such as fix, num and float, as well as math operations. 0:09 We're gonna ask you to build a simple Ruby program that calculates the average of 0:14 some numbers. 0:18 I've attached a work space to this video which includes an average .rb 0:19 starter file, with instructions as Ruby comments. 0:23 You should open the work space now. 0:26 If you have Ruby installed on your computer you can choose file, 0:29 download work space. 0:32 And that will download all the files to your 0:33 computer where you can edit and run them. 0:38 Or you can just set it and run everything in the work space. 0:40 Write your code in the average.rb file and save your work. 0:44 Then switch to the terminal and type ruby average.rb to run your program. 0:47 Up here at the top of the file we've already defined four Ruby 0:53 variables for you. 0:56 Your job is to take the value of all those variables and 0:57 calculate the average, that is the mean of them. 1:00 You can do this by adding all their values together and 1:03 then dividing by the number of values, that's four values in this case. 1:06 Now there's a little catch to this, for the numbers 12, 7, 5 and 10, 1:11 you should get an average of 8.5, not 8. 1:14 If you find that you got the number of 8 even, 1:18 it's probably because you divided by a fixed sum, an integer. 1:21 So make sure that you're dividing by a float instead. 1:24 See the teacher's notes for 1:27 videos that can help you fix this problem if it arises. 1:29 There's an extra credit problem down here at the bottom you can try. 1:33 You can prompt the user for some values to average by populating the E, B, C and 1:35 D variables by calling the get s method. 1:40 Note however, that the get s method returns the string not a number. 1:44 So you'll need to call the to_f method on the value 1:47 returned by gets to convert it to a float. 1:50 That is when we type gets.to_f and then store that value in a variable. 1:53 Then you can calculate an average of all the variables as you did previously. 1:59 I've linked to some videos in the teacher's notes which you can refer to 2:03 if you get stuck. 2:07 After you've written your program you can proceed to the next video 2:09 where you can compare my solution to yours. 2:11 Ready? 2:14 Get started on your program. 2:15 I'll show you my version and the next video. 2:16