*** Click on    to see the whole action ***

To use offline, download and unzip 2balls_v2.zip.

Then, double-click on 2balls.html. How do I do all this?

Scratch file designed by Linda Fahlberg-Stojanovska.

Activity Notes

We have 2 balls - 1 Red and 1 Green. We mix and drop them into a vertical box. What color ball drops first?

The following two events are mutually exclusive and complete.

(a) The green ball will drop first.
 We call this event: Green first.

(b) The red ball will drop first.
 We call this event: Red first.

Guided Activity

Do the experiment 200-1000 times.

  • What is the percent of green first?
  • What is the percent of red first?

Now for some dreaded theory ...

  • Theoretically, how often should the green ball drop first into the box?
  • Theoretically, what is the probability that the red ball will drop first?
  • Does this agree with your experimental results?
  • What other real life situations give this kind of probability?

"Mutually exclusive" means both events cannot happen at same time and "complete" means no other event can occur.

  • To change Scratch file, download and install freeware Scratch. See Scratch-MIT for more information.

Related Topics



 Up one level

Page last modified on December 05, 2008, at 08:55 AM