Please help me

I am doing an exam. there are 8 topics i can choose from. A random four will come up in the exam. If i study 3, what are the odds one of my choices will NOT come up? I think it might be 35-1. Thanks for your help

Using simulation in EXCEL, the chance of:

. all your choices don´t come up is 0.08;
. two of your choices don´t come up is 0.43;
. one of your choices doesn´t come up is 0.42;
. all your choices come up is 0.07.

Total = 1.00

Rui

After having read more carefully your post, I am afraid I have misinterpreted your question. I thought you had been presented with three choices instead of four. Let me correct the answer that I gave you in my last post.

The chance of:

. none of your choices come up is 0.013…all fail;
. only one of your choices come up is 0.240…three fail;
. two of your choices come up is 0.504…two fail;
. three of your choices come up is 0.227…one fails;
. all of your choices to come up is 0.016…none fails.

Total = 1.000

Sorry,

Rui

thanks a lot for your help. i really appreciate it

i was wondering if someone could help me.i have a math paper to complete, but i got stuck on one of the problems.could someone please work it out for me, showing the working out?the problem is
1-10x = 4 + 2x-1
4x^2-9 3-2x 2x+3

This is basic algebra. Just combine the two terms on the right hand side into one by cross-multiplying the denominators. Then the denominators on both sides are the same (multiplied by -1), so you just have to solve a quadratic in x.

If you can't figure it out from that, then I really suggest you go and get a book and learn about algebra, because you're going to come unstuck sooner or later if you don't.



But I expect you've probably posted this question on a number of sites, and somebody somewhere will have answered it for you.

Thanks Zaza, that helped a lot.