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# Events A, B, C and D are all possible outcomes of an experiment. In t

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Re: Events A, B, C and D are all possible outcomes of an experiment. In t [#permalink]
P(x)=P(a)+P(b)+P(c)+P(d)=1
=P(a)+P+0.25+P(c)+P(d)=1
=P(a)+P(c)+P(d)=0.75

Require c and d values

B clearly gives this Vue, A does not

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Re: Events A, B, C and D are all possible outcomes of an experiment. In t [#permalink]
MathRevolution wrote:
[GMAT math practice question] 4.11

Attachment:
4.11.png

Events $$A, B, C$$ and $$D$$ are all possible outcomes of an experiment. In the table above, $$P(x)$$ denotes the probability that event $$x$$ occurs. What is $$P(A)$$?

$$1) P(A)+P(B)+P(C)=0.75$$
$$2) P(C)+P(D)=0.25$$

Looking at St. 1 -
We know that P(B)=.25
and from the st. P(A)+P(B)+P(C)=0.75

So, P(A)+P(C) =.25

No other way to find out the value of P(A).
Insufficient

So, options A & D are out

Now, for st.2
P(C)+P(D)=0.25
and it is given that P(B)=.25

Now, we also know that

P(A)+P(B)+P(C)+P(D)=1

replacing the values,

P(A)+.25+.5=1

P(A) =.25

Hence, B

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Re: Events A, B, C and D are all possible outcomes of an experiment. In t [#permalink]
First of all, I am not that good at probability. So please let me know if my approach is correct or not.

We need to P(A).

St 1: P(A)+P(B)+P(C)=0.75
=>P(B) = 0.25
=>P(A) + P(B) = 0.50
=> We cannot determine the value of P(A) from the given data. Hence insufficient.

St 2: P(C) + P(D) = 0.25
=>P(A)+P(B)+P(C)+P(D)=1
=>P(A)+0.25+0.25=1
=>P(A)=1-0.25-0.25
=>P(A)=0.50

Hence I chose B
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Re: Events A, B, C and D are all possible outcomes of an experiment. In t [#permalink]
The question could be much clearer if it explicitly mentioned that A, B, C and D are the only possible outcomes. Since this is the only way sum of their probabilities will be 1.
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Re: Events A, B, C and D are all possible outcomes of an experiment. In t [#permalink]
All though i got the answer right, i have a doubt about the interpretation of the question stem.
It says "Events A,B,CA,B,C and DD are all possible outcomes of an experiment."
Shouldn't it be "Events A,B,CA,B,C and DD are THE ONLY possible outcomes of an experiment."
Or is that to be understood such cases?
Re: Events A, B, C and D are all possible outcomes of an experiment. In t [#permalink]
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