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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?

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

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15 Jun 2016, 03:04

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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)

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

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09 Oct 2016, 23:53

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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) .

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
_________________

Scott Woodbury-Stewart Founder and CEO

GMAT Quant Self-Study Course 500+ lessons 3000+ practice problems 800+ HD solutions

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

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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

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

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13 Oct 2016, 06:44

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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... _________________

Thanks and Regards

Abhishek....

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

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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) .

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

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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