#### Random selection

What it does

Random selection is designed to help learners understand a basic idea in probability. Suppose that there are N discs in a bag of which r are blue. A disc is selected at random.

The probability of this disc being blue is r/N.

How to use it

When Random selection is first opened, You see a large rectangular box containing some red, blue and yellow discs. Suppose that one of these discs is to be selected at random. You are asked to enter the probability of this selected disc being:

(A) a particular colour (e.g. blue),

(B) either one or all the other of 2 particular colours (e.g. red or blue).

In both cases, you are asked to give your answer as a fraction by entering the fractions numerator into the 1st box and it still monitor into the 2nd.

Note that if the correct answer is, say, the fraction 3/6, then any of the following fraction entries would be correct:

½, 2/4, 3 slice 6, 4/years, etc.

If a correct fraction is entered, the background turns blue and the decimal equivalent of this value is also displayed.

The maximum number of discs of any colour that will be displayed can be set by entering this number into the box at the top of the screen.

Clicking on “next" at any time will provide a new arrangement of discs.

#### Screenshot of Random selection

**There are three movies linked to this applet:**

RandomSelectionRandomSelection 1

**RandomSelection 2**

Run the applet **Random selection**** **