http://imgur.com/AMb963Z

i need help with 1b and 11b.

1b)
i know that p(A) = .5
and p(b) = .5
how would i expand the conditonal probability?

and 11b)
do i set the probability equal to .99? and solve for x?

I don't know the answers, but I embedded the image so it's easier for others.

ok i appreciate it

1b
The question is asking. What is the probability of A intercet B given that you are in the area where A union B. And then multiply that by the probability of A.

So you can rewrite it as
P( 100<=x<200 | 0<= X < 300) * 1/2.
And the conditional probability is 1/3 (1/4 chance of 100<=x<200, 3/4 chance of 0<= X < 300)
so your final answer is 1/6

11. That is correct, get a 99% confidence ratio, take the largest number and round up. Or be a smart ass and write 50 million.

EDIT:EDITED

This post was edited by lebensohl on Oct 20 2013 10:59pm

oh wow thanks bro, i had 1/6 too but i did P(A intersect B ) = P(A)P(B) and P(A U B)= P(A) + P(B) - P(A)P(B)
and then just divide then mutiply by P(A). wasnt too sure though cuz of the notation it was written in..
i understand it better through ur work though lol

hmm i dont really get wat the question is askin, wat does it mean? can u explain. i dunt get the 50 million part lol
I did P(Z > x) = .99
2.33 = x - 1 / .32

x = 1.7456?

not sure if my equality signs r correct,, i always get confuse wit those lol

Remember to multiply x by 2000 and you are good :). You got it correct.

Why do u multiply by 2000