It follows the same logic as P(Not A) = 1 - P(A)

P( X = 7 to n) = 1 - P(x = 0 to 6). If X =7 is part of one end of the probability, then the other half cannot include 7 as well.

Reply 146

sasunerd

1

Original post by DarkWillow

I can't quite get my head around why P(X>=7) = 1 - P(X<6)
Can anyone explain why or help me understand that? lol

With P(X>=7) it only includes the numbers from 7 and upwards, therefore to get that value, you have to take away the numbers before 7 ie 6543210 to get the answer, leading to 1-P(X<=6)

Reply 147

Bob Ahmed

Original post by DarkWillow

I can't quite get my head around why P(X>=7) = 1 - P(X<6)
Can anyone explain why or help me understand that? lol

Because P(X≥7) is the probability of 7 happening or more, which means that it is 7,8,9,10 etc.. to n. To find this probability, you would need to subtract P(X≤6) from the total probability which is 1 (it always adds up to 1).

Basically you are just checking what is left from the total probability(1).

Hope this helped... kinda lol

Reply 148

DarkWillow

11

Thanks you 3! All 3 helped me so much! It always ruined my null hypothesis questions, but I get it now!! :'D

Reply 149

dada55

19

Original post by DarkWillow

Thanks you 3! All 3 helped me so much! It always ruined my null hypothesis questions, but I get it now!! :'D

Just be careful with the wording/notation they use as to whether its "> "or ">=".

at least: >=
more than: >
less: <
less or equal to: =<

So P(X>6) = 1 - P(X=<6)

as P(X>6) = 7,8,9...n

so the leftovers are 0,1,2...6

Reply 150

DarkWillow

11

I've done Jan 2008, June 2008, Jan 2011, Jun 2011, Jan 2012, Jan 2013 papers.
I also did bits of 2009 & 2010 in class, Hopefully I can get 85% UMS in this!

Reply 151

DarkWillow

11

Original post by dada55

Just be careful with the wording/notation they use as to whether its "> "or ">=".

at least: >=
more than: >
less: <
less or equal to: =<

So P(X>6) = 1 - P(X=<6)

as P(X>6) = 7,8,9...n

so the leftovers are 0,1,2...6

Okay, Thanks! I'll just make notes along my paper writing out all the numbers that are valid for the expression!