Bunuel wrote:

Bakshi121092 wrote:

Bunuel wrote:

[quote="Bakshi121092"]

Hi Bunuel,

What is wrong in the following approach?

Cases considered :

1. Born in a leap year

2. Not born in a leap year

In that case, the probability of not born in a leap year =1/2

And subsequently, the probability that at least one of them is born in a leap year would turn out to be greater than 50% for 2 people.

Please help.

Thank you.

Let me ask you: is the probability that you win a lottery 1/2?

1. You win the lottery

2. You won't win the lottery

Or: what is the probability to meet a dinosaur on the street? Is it 1/2? Either you meet it or not?

22. Probability

For more:

ALL YOU NEED FOR QUANT ! ! !Ultimate GMAT Quantitative Megathread.

I understand. But the question doesn't mention a time frame.

For example, considering the probability to be 3/4 is for any 4 year time frame. If we consider a 5 year time frame, the probabilities change.

The probabilities you asked depend on other factors. One can simply not tell. But with no other information given, the probability that I could meet a dinosaur would be 1/2. I may or may not encounter a dinosaur.

Please help.

Thanks.

That's not correct.

There is one leap year in four. So, the probability of random person being born in leap year is 1/4. As for the dinosaur problem, no other information is needed apart from common knowledge, the probability is not 1/2: meeting and not meeting are not equally likely, and simply the fact that there are only two options does not mean that the provability is 1/2.

I suggest you to follow the links given in my previous post and maybe read some simple book on probability (introduction of some kind).[/quote]Sure I'll look into it. I get the understanding now.

Thanks for the help.

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