If the probability of Ronaldo will do at least 3 goals in the match is

I think there is an Error.
Ans A:
Neither of the two event will occur = Probability= .27*.41 = .1107

Hey,

It's a trick question actually.

There is no mistake in it. I would request you to go through the following article and read Probability in Dependent Events to understand this question.

3 deadly mistakes you must avoid in Probability

There is a similar question asked in GMATPrep, here is the link : Click Here

Hey,

Unfortunately your answer is not correct.

I would request you to go through the following article and read Probability in Dependent Events to understand this question.

3 deadly mistakes you must avoid in Probability

There is a similar question asked in GMATPrep, here is the link : Click Here

Since the event that Ronaldo will score atleast 3 goals in the match and Ronaldo's team
winning the match are dependant, in order to find the greatest probability that neither
of the events occur, we need to find the individual probabilies:

P(Ronaldo doesn't score 3 goals) = 1 - P(Ronaldo scores 3 goals) = 1 - 0.59 = 0.41
P(Ronaldo's team doesn't win the match) = 1 - P(Ronaldo's team wins) = 1 - 0.73 = 0.27

Therefore, the greatest probability that neither of the events take place is 0.27 (Option B)


P.S Here, the greatest probability that neither of the events will occur is the probability
of the more probable event(Ronaldo's team winning the match) not occuring.

pushpitkc



Yet another tip learnt from your post. Thanks much

Please clarify how you reached to this conclusion ? I am still not able to understand this. because if Neither of the event will occur means, as i understand, neither of these two event occur together.. I am really confused with this language of the question.

P(R3) = Ronaldo scores 3+ = 0.59
P(T) = Team wins = 0.73.

To find Max[P(R3+T)'] =Max[1-P(R3+T)]

Now, P(R3+T) = P(R3)+P(T)-P(R3T) = 1.32 - P(R3T)
P(R3+T)' = P(R3T) - 0.32.

Now comes the trick, since they are dependent events P(AB)<= min[P(A),P(B)] . This is a standard relation of probability for dependent events. If you want clarification just draw the 2 sets. Since P(AB) is the common region it cannot exceed the minimum of P(A), P(B) [This occurs when A is a subset of B].

So, Max[P(R3+T)'] = 0.59 (Team wins) - 0.32 = 0.27.

This a very good question.

Hey,
This question is actually a tricky question.

This is a question of dependent probability- When the occurrence or non-occurrence of one event depends on another event.
For example: If the price of raw material decreases then the product becomes cheap, right???
Thus, both the events are dependent on each other.

And we have thoroughly explained how to avoid the error in the case of dependent event in the article- 3 deadly mistakes you must avoid in Probability.

Hope it helps.
Regards,
Ashutosh

Hey everyone,

The official answer to the question has been posted.

Regards,
Ashutosh

Thank you for the explanation. I thought Ronaldo can make at least 3 goals and a team can still lose a match, or win a match even if Ronaldo makes less than 3 goals, and misunderstood that this is the question of independent probability..

I get your point but I think the question is flawed because in essence the events are not dependent. Ronaldo could also score 500 goals if the other teams scores 1 more Ronaldos Team would loose. Also another Team member other than Ronaldo could lead the team to a win. How are we supposed to know that those events are dependent?

Hi,
I got your point and it is really a little the meaning regarding what the question is asking is subtle.

Actually, what you said makes sense: the team can win, having Ronald marked >= 3 goals or <3. Or even vice versa, rigth?
I agree with you.
They are indepedent if you think about one of them independently, as the other doesn't exist.

But, what would you say if you were asked "what are the odds of Ronald marks three or more goals and the team wins?"

In this case, you've changed the scenario, you have a new scenario. The scenarios (goals of Ronald and team win) now are coexisting and can have intersections!
For the sake of illustration, we can have now the following outcomes:

Ronald scores 3 or more goals AND Team wins
Ronald scores 3 or more goals AND Team loses
Ronald scores less than 3 goals AND Team wins
Ronald scores less than 3 goals AND Team loses


Well, what I mean by this is that in a given scenario when we have two or more events (let's say A, B, C,...), they are called Dependent Events when they have intersection (not empty, of course) with each other. And when they don't have any intersection, they are called independent.

Some of these explanations seem apt to confuse.

It's not necessary to know whether the events are dependent or independent.

The question itself, asking for the maximum, forces the consideration of dependence because that is the scenario that generates the maximum result.

Independent events, X*Y vs min[X and Y] for dependent.

X*Y is always less than min[X and Y] when X,Y<1.

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