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The chance of rain in Dennyville is 40% on Monday and 80% on
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01 Apr 2020, 09:23
01 Apr 2020, 09:23
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67% (01:02) correct
32% (01:10) wrong based on 53 sessions
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The chance of rain in Dennyville is 40% on Monday and 80% on Tuesday. What is the probability that it rains in Dennyville on at least one of these two days?
A. 120%
B. 88%
C. 76%
D. 60%
E. 32%
Kudos for the right answer and explanation
A. 120%
B. 88%
C. 76%
D. 60%
E. 32%
Kudos for the right answer and explanation
Retired Moderator
Joined: 10 Apr 2015
Posts: 6218
Given Kudos: 136
Re: The chance of rain in Dennyville is 40% on Monday and 80% on
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01 Apr 2020, 09:37
01 Apr 2020, 09:37
1
Carcass wrote:
The chance of rain in Dennyville is 40% on Monday and 80% on Tuesday. What is the probability that it rains in Dennyville on at least one of these two days?
A. 120%
B. 88%
C. 76%
D. 60%
E. 32%
Kudos for the right answer and explanation
A. 120%
B. 88%
C. 76%
D. 60%
E. 32%
Kudos for the right answer and explanation
We want P(at least one day of rain)
When it comes to probability questions involving "at least," it's usually best to try using the complement.
That is, P(Event A happening) = 1 - P(Event A not happening)
So, here we get: P(at least one day of rain) = 1 - P(not getting at least one day of rain)
What does it mean to not get at least one day of rain? It means getting zero rain.
So, we can write: P(getting at least one day of rain) = 1 - P(getting zero days of rain)
P(getting zero days of rain)
P(getting zero days of rain) = P(no rain on Monday AND no rain on Tuesday)
= P(no rain on Monday) x P(no rain on Tuesday)
Given: P(rain on Monday) = 40% = 0.4, which means = P(NO rain on Monday) = 60% = 0.6
Given: P(rain on Tuesday) = 80% = 0.8, which means = P(NO rain on Tuesday) = 20% = 0.2
So, P(getting zero days of rain) = 0.6 x 0.2
= 0.12
So, P(getting at least one day of rain) = 1 - 0.12
= 0.88
= 88%
Answer: B
Cheers,
Brent
Re: The chance of rain in Dennyville is 40% on Monday and 80% on
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24 Jun 2021, 04:49
24 Jun 2021, 04:49
Hello from the GRE Prep Club BumpBot!
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Thanks to another GRE Prep Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).
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