Mathematics help

by **oggiss** on Thu Feb 07, 2008 5:38 am

This is kinda newbie maths, but I need help.

Question:

Adams probability to catch the train is 0.7
Simons probability to catch the train is 0.8

What is the probability that at east ONE of them catches the train?

Anyone? :/

by **yeti_c** on Thu Feb 07, 2008 5:42 am

0.75

C.

by **oggiss** on Thu Feb 07, 2008 5:42 am

yeti_c wrote:0.75

C.

I have 5 alternatives, and not one of them is 0.75 :/

by **Skittles!** on Thu Feb 07, 2008 5:48 am

PSH!

Give us the alternatives and I may be able to think it out for you.

by **oggiss** on Thu Feb 07, 2008 5:51 am

Skittles! wrote:PSH!

Give us the alternatives and I may be able to think it out for you.

0.56 <--- Not possible.

0.92

0.94

0.96

0.98

by **edbeard** on Thu Feb 07, 2008 5:54 am

P(A or B) = P(A) + P(B) - P(A and B)

when we say P(A or B) here we mean A can occur, B can occur, or both.

P(A and B) here means P(A)*P(B). Since (I assume) we are assuming whether Adam and Simon catch the train are independent of each other (Adam catching the train doesn't affect whether Simon catches the train)

by **Skittles!** on Thu Feb 07, 2008 5:54 am

Yeah, I have no idea because I forget all of my probability. Ha. I forget the formula to do it <<

How is it not possible though?

by **SirSebstar** on Thu Feb 07, 2008 5:56 am

Question:

Adams probability to catch the train is 0.7
Simons probability to catch the train is 0.8

What is the probability that at east ONE of them catches the train?

noteto me:first read then think, so if one has 80% of making it, and the other 70%, it does not matter if both have to take it, just that one does.
so we start with 80%, that being the highest. then in the remaining 20% there is still a 70% chance for adam to catch the train.
(pray he gets it rigth)

That’s 80% PLUS 70% of the remaining 20% for a total of:
80+ (70%x20)= 94%

by **oggiss** on Thu Feb 07, 2008 5:57 am

edbeard wrote:P(A or B) = P(A) + P(B) - P(A and B)

when we say P(A or B) here we mean A can occur, B can occur, or both.

P(A and B) here means P(A)*P(B). Since (I assume) we are assuming whether Adam and Simon catch the train are independent of each other (Adam catching the train doesn't affect whether Simon catches the train)

Dude, you can't use that formula can you, since they aren't depending on each other.

IRT #Skittles

Because the lowest probability is 0.7, which there total must be over.

by **oggiss** on Thu Feb 07, 2008 5:57 am

Someone get sully800 here :/

IRT SirSebster

I don't really know how you solve that equation? :/

by **edbeard** on Thu Feb 07, 2008 6:00 am

oggiss wrote:Dude, you can't use that formula can you, since they aren't depending on each other

that's exactly why you CAN use it.

.8 + .7 - (.8*.7) = 1.5 - .56 = .94

by **SirSebstar** on Thu Feb 07, 2008 6:00 am

i edited it to make it more comprehensible
i hope its understandable now

by **oggiss** on Thu Feb 07, 2008 6:02 am

edbeard wrote:
oggiss wrote:Dude, you can't use that formula can you, since they aren't depending on each other

that's exactly why you CAN use it.

.8 + .7 - (.8*.7) = 1.5 - .56 = .94

Seems to be the right equation

Thanks both sebster and edbeard

by **oggiss** on Thu Feb 07, 2008 7:34 am

http://www.glamdring.se/files/oggiss.20 ... .33.14.gif

Can anyone solve that one?

The figure shows a white area, I wanna know what the sign is of it in mathematic language. Like those A and B's there.

Thank you

by **yeti_c** on Thu Feb 07, 2008 7:39 am

It's just A...

(i.e. Option C)

C.

by **oggiss** on Thu Feb 07, 2008 7:50 am

yeti_c wrote:It's just A...

(i.e. Option C)

C.

k thanks

by **alex_white101** on Thu Feb 07, 2008 7:59 am

yeti_c wrote:It's just A...

(i.e. Option C)

C.

i agree

by **yeti_c** on Thu Feb 07, 2008 8:02 am

alex_white101 wrote:
yeti_c wrote:It's just A...

(i.e. Option C)

C.

i disagree, i think its either A or B, as it is A including B but i cant remember which one it is.

a) is the Intersection of A & B - i.e. the bit in the middle...
b) is the Union of A & B - i.e. All of the area not including the bit in the middle
c) is just A (Which is the white area)
d) is just B which would be the contents of the circle named B

http://en.wikipedia.org/wiki/Table_of_m ... al_symbols

C.

by **alex_white101** on Thu Feb 07, 2008 9:23 am

yeti_c wrote:
alex_white101 wrote:
yeti_c wrote:It's just A...

(i.e. Option C)

C.

i disagree, i think its either A or B, as it is A including B but i cant remember which one it is.

a) is the Intersection of A & B - i.e. the bit in the middle...
b) is the Union of A & B - i.e. All of the area not including the bit in the middle
c) is just A (Which is the white area)
d) is just B which would be the contents of the circle named B

http://en.wikipedia.org/wiki/Table_of_m ... al_symbols

C.