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The probability that event M will not occur is 0.8 and the probability

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The probability that event M will not occur is 0.8 and the probability [#permalink]

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The probability that event M will not occur is 0.8 and the probability that event R will not occur is 0.6. If events M and R cannot both occur, which of the following is the probability that either event M or event R will occur?

A) 1/5
B) 2/5
C) 3/5
D) 4/5
E) 12/25
[Reveal] Spoiler: OA

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The probability that event M will not occur is 0.8 and the probability [#permalink]

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New post 15 Jun 2016, 02:52
p(m) =0.2
p(r) =0.4
p(m intersection r) = 0 (If events M and R cannot both occur)
p(m or r) = 0.2+0.4 =0.6

Corrected !!

Last edited by CounterSniper on 15 Jun 2016, 03:31, edited 1 time in total.

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Re: The probability that event M will not occur is 0.8 and the probability [#permalink]

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Bunuel wrote:
The probability that event M will not occur is 0.8 and the probability that event R will not occur is 0.6. If events M and R cannot both occur, which of the following is the probability that either event M or event R will occur?

A) 1/5
B) 2/5
C) 3/5
D) 4/5
E) 12/25


P(R) = 1 - 0.8= 0.2
P(M) = 1 -0.6 = 0.4

Given that both events are mutually exclusive.

Prob that either event M or event R will occur = 0.2+0.4 = 0.6 = (6/10) = (3/5)

C is the answer.

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Re: The probability that event M will not occur is 0.8 and the probability [#permalink]

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Got it wrong.

p(m) =0.2
p(r) =0.4

So, I calculated probability as sum of:

i) m occurs but r does not occur = 0.2*0.6
ii) r occurs but m does not occur = 0.4*0.8

So, probability = 0.2*0.6 + 0.4*0.8 = 0.44 = 11/25!

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Re: The probability that event M will not occur is 0.8 and the probability [#permalink]

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Just made a mistake by multiplying 0.2 and 0.4, got \(\frac{2}{25}\)

Note to self: "multiply" when there is an "AND", and "add" when there is an "OR"

we should be adding 0.2+0.4 = 0.6 or \(\frac{3}{5}\)
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Re: The probability that event M will not occur is 0.8 and the probability [#permalink]

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New post 26 Sep 2016, 17:55
Can someone please explain why is it not
0.8*0.4+0.2*0.6
11/25
:?

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Re: The probability that event M will not occur is 0.8 and the probability [#permalink]

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shonakshi wrote:
Can someone please explain why is it not
0.8*0.4+0.2*0.6
11/25
:?



I think , you are trying to calculate probability by multiplying P(M)*P(~R) + P(R)*P(~M) . This is wrong .
Formula is P(M or R) = P(M) + P(R) - P (M and R) => 0.2 + 0.4 - 0 = > 0.6 or 3/5 (Answer is C) .

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The probability that event M will not occur is 0.8 and the probability [#permalink]

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shonakshi wrote:
Can someone please explain why is it not
0.8*0.4+0.2*0.6
11/25
:?


Go through this page, it will answer all your queries...

https://people.richland.edu/james/lectu ... 5-rul.html

Hope that helps..
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The probability that event M will not occur is 0.8 and the probability [#permalink]

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Bunuel wrote:
The probability that event M will not occur is 0.8 and the probability that event R will not occur is 0.6. If events M and R cannot both occur, which of the following is the probability that either event M or event R will occur?

A) 1/5
B) 2/5
C) 3/5
D) 4/5
E) 12/25


We are given that the probability that event M will not occur is 0.8 and the probability that event R will not occur is 0.6 and that events M and R cannot both occur.

We need to determine the probability that either event M or event R will occur.

The probability that event M will occur is 1 - 0.8 = 0.2 = 1/5

The probability that event R will occur is 1 - 0.6 = 0.4 = 2/5

Since events M and R cannot both occur , the probability that either event M or event R will occur is 1/5 + 2/5 =3/5.

Answer: C
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Re: The probability that event M will not occur is 0.8 and the probability [#permalink]

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New post 13 Oct 2016, 04:01
ScottTargetTestPrep wrote:
Bunuel wrote:
The probability that event M will not occur is 0.8 and the probability that event R will not occur is 0.6. If events M and R cannot both occur, which of the following is the probability that either event M or event R will occur?

A) 1/5
B) 2/5
C) 3/5
D) 4/5
E) 12/25


We are given that the probability that event M will not occur is 0.8 and the probability that event R will not occur is 0.6 and that events M and R cannot both occur.

We need to determine the probability that either event M or event R will occur.

The probability that event M will occur is 1 - 0.8 = 0.2 = 1/5

The probability that event R will occur is 1 - 0.6 = 0.4 = 2/5

Since events M and R cannot both occur , the probability that either event M or event R will occur is 1/5 + 2/5 =3/5.

Answer: C




We should take into consideration that both cannot occurs. please explain

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Re: The probability that event M will not occur is 0.8 and the probability [#permalink]

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Bunuel wrote:
The probability that event M will not occur is 0.8 and the probability that event R will not occur is 0.6.If events M and R cannot both occur, which of the following is the probability that either event M or event R will occur?

A) 1/5
B) 2/5
C) 3/5
D) 4/5
E) 12/25


M' = 0.80 So M = 0.20
R' = 0.60 So R = 0.40
Quote:
probability that either event M or event R will occur?

M+R = M + R - MR
Quote:
events M and R cannot both occur

So , MR = 0

M+R = 0.20 + 0.40 - 0

Or, M+R = 0.60

Hence answer will be 0.60 or (C) 3/5

SOHAM6185 wrote:
We should take into consideration that both cannot occurs. please explain


The reason is highlighted...

Try to solve this question using VENN Diagram approach it will be crystal clear...
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Re: The probability that event M will not occur is 0.8 and the probability [#permalink]

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New post 30 Jun 2017, 02:45
sb0541 wrote:
shonakshi wrote:
Can someone please explain why is it not
0.8*0.4+0.2*0.6
11/25
:?



I think , you are trying to calculate probability by multiplying P(M)*P(~R) + P(R)*P(~M) . This is wrong .
Formula is P(M or R) = P(M) + P(R) - P (M and R) => 0.2 + 0.4 - 0 = > 0.6 or 3/5 (Answer is C) .


yes, that is why p(m and n) need to be zero.

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Re: The probability that event M will not occur is 0.8 and the probability [#permalink]

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New post 08 Nov 2017, 16:00
shonakshi wrote:
Can someone please explain why is it not
0.8*0.4+0.2*0.6
11/25
:?


The probability that event M will not occur is 0.8 and the probability that event R will not occur is 0.6. If events M and R cannot both occur, which of the following is the probability that either event M or event R will occur?

Let's break this down

M will not occur = 0.8; M will occur = 0.2
R will not occur = 0.6; R will occur = 0.4

P(M or R) = P(M) + P(R) - P (M and R)
P(M or R) = 0.2 + 0.4 - 0
P(M or R) = 0.6 = 6/10 = 3/5

Note: Multiplying occurrence that will not occur + Multiplying occurrence that will occur is not equal to either event M or event R will occur

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Re: The probability that event M will not occur is 0.8 and the probability   [#permalink] 08 Nov 2017, 16:00
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