Math Is Fun Forum

thanks

Yeah. See, I knew it was simple. Been staring at the problem too long.

Thanks

I don't know what you mean. All the signs are negative, so how have I not changed a sign. Can you write it out for me because I can't see why it's wrong.

I'm still not getting the right answer. It's supposed to be 4., apparently, and I'm getting -1. (I don't even know how it's possible to get a minus for area).

Headache

(and thanks for the help)

ahh. thanks

(I'd like to get a second opinion on this, as I have just started statistics, and I had never seen a Venn diagram before last month. I'll ask my stats teacher tomorrow when I'm in if you like, or maybe a more advanced member can tell me if I've got this right).

P(A or B) means the chances that A or B occur. So add the A circle and the B circle.. Remember that the 0.15 can occur both in A and B, so make sure you count it, but be careful not to count it twice. (I work it out to be 0.99)

P(A' and B') means the complement of A (the total of A not occurring) and the Compliment of B (the total of B not occurring). I'm hoping someone h=will correct me if I'm wrong, but I'd read that as A not occurring and B not occurring. When you add up all the decimals, you get 0.99. That means that the chances of none of these events happening is 0.01) as the total must be 1).

P(A/B) means given A, The chances of B then happening. So if A has happened (this is the denominator) what is the chances of B happening (the numerator).

I really need to check my workings, because I am unsure whether the intersection has been counted twice in my workings, I believe it has. But the notation is right: The A' means compliment (anything that is not A) and A/B means given A happening, chances of B happening.

Anon, I was wondering that as well, actually. I might ask my teacher than tomorrow.

Why is the integration not right? Is it because it's missing the denominators for the 2x3^2 and 2x-1^2

(sorry if I'm not making a lot of sense. I've been doing calculus all day)

Okay, so next part of the question. (I can't do the notation on here so I'm just going to write it without the correct notation).

Intergrating 5+2x-x^2.
=5x+2x^2 - x^3
        ------  ------
          2         3

Then supplement the two coordinates in for x
= (5x3 + 2x3^2 - x^3  ) - (5x-1 + 2x-1^2 - -1^3)
              -------   ------                 --------     -----
                 2         3                         2            3

and that's where I get a bit unstuck. The first part is easy enough:

=15 +9 -3) - (this is the bit i am sure I have wrong)

I don't want to sound dumb, but could you just put the solving up? I think I have it, but I just need to double check I've done it right. (My biggest problem is confidence)