Well - to make it a little easier - if you copy and paste the diagram into windows notepad (or some text editor) it becomes clearer to read -

(Roger - you should try the 'pre' command in front of and after the diagram = left arrow, the word pre, then right arrow and end with left arrow, slash, the word pre then right arrow - it may help the format)

As far as extra credit (I always take advantage of that in school!) - '2 or more' and 'more than one' seem to define the same thing to me. But - if I understand the 'assignment' 2 or more and more than one seem to be satisfied in sets 2,3,4 & 5 - 3 or more in sets 3, 4 & 5.

All sets have at least one quake so they do satisfy all 3 definitions. One bit of trouble with the 3 definitions is that you might always be right with all 3 statements if aftershocks are included - if its a large quake aftershocks are likely to follow so at least one and one or more will be satisfied.

One thing that bothers me - about 42% of the time is covered with a prediction - that doesn't seem to be very useful.

Canie