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S1 Help!

If A and B are two events and P(A) = 0.6, P(B) = 0.3 and P(A U B)=0.8, find:

(a) P( A n B)
(b) P( A' n B)
(c) P (A n B')
(d) P (A' n B')
(e) P (A U B')
(f) P (A' U B)

Please explain!
Reply 1
Avatar for You
You
OP
Anyone?
Reply 2
Avatar for You
You
OP
....
Reply 3
Avatar for nas7232
nas7232
19
If A and B are two events and P(A) = 0.6, P(B) = 0.3 and P(A U B)=0.8, find:

(a) P( A n B)
(b) P( A' n B)
(c) P (A n B')
(d) P (A' n B')
(e) P (A U B')
(f) P (A' U B)

a) probability of A and B = 0.6 x 0.3
b) probability of B but not A = 0.4 (1-0.6) x 0.3
c) probability of A but not B = 0.6 x 0.7
d) probability of not A & not B = 0.4 x 0.7
e) probability of A or Not B = 0.6 + 0.7
f) probability of Not A or B = 0.4 + 0.3

:smile:
Reply 4
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You
OP
htanks BUT answers in the book:

0.1
0.2
0.5
0.2
0.8
0.5
Reply 5
Avatar for nas7232
nas7232
19
mmh thats odd. The rules are correct, maybe i did something wrong...

Is "If A and B are two events and P(A) = 0.6, P(B) = 0.3 and P(A U B)=0.8, find" correct"?

P(A U B)=0.8 - means probability of A union B ~ P(A) or P(B) which is P(A) + P(B)
Reply 6
Avatar for TheWolf
TheWolf
15
nas7232
If A and B are two events and P(A) = 0.6, P(B) = 0.3 and P(A U B)=0.8, find:

(a) P( A n B)
(b) P( A' n B)
(c) P (A n B')
(d) P (A' n B')
(e) P (A U B')
(f) P (A' U B)

a) probability of A and B = 0.6 x 0.3
b) probability of B but not A = 0.4 (1-0.6) x 0.3
c) probability of A but not B = 0.6 x 0.7
d) probability of not A & not B = 0.4 x 0.7
e) probability of A or Not B = 0.6 + 0.7
f) probability of Not A or B = 0.4 + 0.3

:smile:


the first one you can just use the addition rule..e.g.

0.8 = 0.6 +0.3 - p(A n B)
Therefore P(A n B) = 0.1
Reply 7
Avatar for nas7232
nas7232
19
Isn't it P( A n B) which means A and B :s-smilie: ~ A X B
Reply 8
Avatar for TheWolf
TheWolf
15
nas7232
Isn't it P( A n B) which means A and B :s-smilie: ~ A X B


no lol. Do you do stats modules?
Reply 9
Avatar for nas7232
nas7232
19
Yeah i got a B for s1

Repeating this year to try n get near 100%

Haven't done stats in a while, i scheduled revision for april ish.

Whats the "lol" for, that's not very nice issit.

..looked in my edexcel book; got signs mixed up. Ignore the answers :smile:
Reply 10
Avatar for TheWolf
TheWolf
15
It was a friendly lol. :smile:
Reply 11
Avatar for Jonny W
Jonny W
8
Use a Venn diagram.

P(A n B) = P(A) + P(B) - P(A u B) = 0.1
P(A' n B) = P(B) - P(A n B) = 0.2
P(A n B') = P(A) - P(A n B) = 0.5
P(A' n B') = 1 - P(A u B) = 0.2
P(A u B') = 1 - P(A' n B) = 0.8
P(A' u B) = 1 - P(A n B') = 0.5

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