Statisticis

*will be exactly 7.
How do you answer this?

Find how many numbers there are between 6.8 and 22.8.
Find how many 7 there are.

Probability of having a 7 is given as (number of 7)/(number of numbers between 6.8 and 22.8)

I'm not positive but I think it's a bit of a trick question. Unless you have some statistics on the numbers people actually end up picking, seems to me it would otherwise be a uniform distribution. In which case, the probably of "exactly" any one number is zero.

Unky, you're trying ot use a typical probability equation that is number of ways for the answer you're looking for divided by the total possible ways something can come out.

So how many ways are there for a seven to be picked? One. How many ways are there for 6.8 through 22.8 to be picked? Uh, can't really answer that. What are the possible outcomes for that? Seems to me rather infinite.

I suspect in reality it's not uniform cause I bet people, for psychological reasons, tend to pick certain numbers. But without testing it, it seems it would be uniform - that is, everything having an equal chance. Which goes back to what I originally said.

But I fully admit I'm not sure about this.

I know morgaine. The problem is... there is no sample space given! Perhaps the OP had it but didn't mention it... so I post the usual way to do it just in case.

That's kind of the point. We are not given a choice of 6.8, 7.0, 7.2, 7.4, etc. or something like that. It's an interval and any number along that line can be picked. There's nothing in those rules saying I can't pick 6.9281987 if I choose.

Making, it my mind, continuous rather than discrete. Re-thinking it, I wouldn't think it uniform cause really, what's the chances someone answers 6.9281987? But more importantly, seems like it's continuous. A continuous distribution isn't going to have a definitive set of sample points.

While there's only one way to pick a 7, how many ways are there to pick a number between 6.8 and 22.8? How do you answer that?

Of course, OP is supposed to know what chapter s/he is in, and should post back if there's more details. Difficult out of context.