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# If the probability that Green Bay wins the Super Bowl is 1/12 and the

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Math Expert
Joined: 02 Sep 2009
Posts: 53066
If the probability that Green Bay wins the Super Bowl is 1/12 and the  [#permalink]

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04 Feb 2015, 07:56
2
00:00

Difficulty:

45% (medium)

Question Stats:

72% (02:00) correct 28% (01:59) wrong based on 166 sessions

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If the probability that Green Bay wins the Super Bowl is 1/12 and the probability that Milwaukee wins the World Series is 1/20, what is the approximate probability that either Green Bay wins the Super Bowl or Milwaukee wins the World Series?

A. 1/240
B. 1/12
C. 1/8
D. 1/7
E. 4/3

Kudos for a correct solution.

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Manager
Joined: 14 Sep 2014
Posts: 106
Concentration: Technology, Finance
WE: Analyst (Other)
Re: If the probability that Green Bay wins the Super Bowl is 1/12 and the  [#permalink]

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04 Feb 2015, 08:26
1
3
Winning the Super Bowl and winning the World Series are independent events; one outcome does not affect the other outcome.

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

1/12 + 1/20 - (1/12 * 1/20)
= 5/60 + 3/60 - 1/120
= 8/60 - 1/120
= 16/120 - 1/120
= 15/120
= 1/8

Math Expert
Joined: 02 Aug 2009
Posts: 7335
Re: If the probability that Green Bay wins the Super Bowl is 1/12 and the  [#permalink]

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04 Feb 2015, 08:35
the two events being independent gives us P(super bowl,world cup)=not winning super bowl*winning world cup + winning super bowl*not winning world cup =19/20*1/12+1/20*11/12=30/240=1/8 ans C
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1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html
4) Base while finding % increase and % decrease : https://gmatclub.com/forum/percentage-increase-decrease-what-should-be-the-denominator-287528.html

GMAT Expert

Math Expert
Joined: 02 Sep 2009
Posts: 53066
Re: If the probability that Green Bay wins the Super Bowl is 1/12 and the  [#permalink]

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09 Feb 2015, 04:23
Bunuel wrote:
If the probability that Green Bay wins the Super Bowl is 1/12 and the probability that Milwaukee wins the World Series is 1/20, what is the approximate probability that either Green Bay wins the Super Bowl or Milwaukee wins the World Series?

A. 1/240
B. 1/12
C. 1/8
D. 1/7
E. 4/3

Kudos for a correct solution.

VERITAS PREP OFFICIAL SOLUTION:

The probability of “X or Y” can be expressed as (Prob X) + (Prob Y) - (Prob of Both). In our case, this is 1/12 + 1/20 – (1/12 * 1/20), or 20/240 + 12/240 – 1/240, or 31/240, which is approximately 1/8.
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Senior Manager
Joined: 08 Dec 2015
Posts: 291
GMAT 1: 600 Q44 V27
Re: If the probability that Green Bay wins the Super Bowl is 1/12 and the  [#permalink]

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18 Jun 2016, 05:14
This one is mathematically strange,

If you use the formula P(A or B) you get 31/240

If you use the formula P(A) * P(not B) + P(B) * P(not A) you get 1/8 !!!

How is this possible?.. Both methods are correct I think and we get a different result?... (very close but math is an exact science, right?)
Intern
Joined: 17 Sep 2011
Posts: 21
Location: United States
If the probability that Green Bay wins the Super Bowl is 1/12 and the  [#permalink]

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02 Dec 2017, 09:34
Hi ,

As has been discussed above posts , P(AUB) = P (A)+ P (B)- P( Both A and B)

= 1/12 + 1/20 -( 1/12*1/20)
~ 1/12 + 1/20 ( since 1/ 240 will be too small and considering less time duriing exam, we can ignore that)
~ 32/240 = 2/15 = 0.13
approximately equal to 1/8 ( 0.125)

If the probability that Green Bay wins the Super Bowl is 1/12 and the   [#permalink] 02 Dec 2017, 09:34
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