Math Is Fun Forum

If 2 pebbles are placed in a random square of a square grid having 64 squares,  then what is the probability of the pebbles being on the same row or column?

I have no idea as to how I should work this out.  Help please!

Have you read H.G. Wells' "The Time Machine"?

I had, a few years ago, and I was thinking about it today. In the first or second chapters, there was a small paragraph, where the Time Traveler explains how he realised that time is a dimension, thereby proposing that we live, not in a 3 dimensional world, but in a 4 dimensional one.

The book is (unfortunately) now in another city, so I can't say it quote-for-quote. But here's what I do remember -

Let's say I make a cube. There are, according to most people, three dimensions, namely, Length, Breadth and Height. The names might change but the inherent meaning does not.
Now, I, being a most dutiful person, make a cube including all of these dimensions, LBH, but do you really think that cube, for all its worth, will exist?

Will it be a real, tangible cube?

Will it truly just be there?

Well, no.

For a very simple reason: the cube does not last. It does not last for the trillionth of a billionth of a second. It's non-existent without time. Length, Breadth and Height are not worth anything without it. Thus, time is equally important as them. If not more.

So we conclude (said the Time Traveler): "Time is a dimension."

Now for my question: Is this true? Is this a logical, feasible idea or is it just absurd fiction with scientific jargon?

What do you think?