destroyer QR #103

[far123]

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two numbers between 1 and 30 inclusive are drawn in a contest. what is the probility that both numbers are even?
the answer is 1/2x1/2=1/4
I think it should be 15/30x14/29, am I right?

 

[boxdesker]

two numbers between 1 and 30 inclusive are drawn in a contest. what is the probility that both numbers are even?
the answer is 1/2x1/2=1/4
I think it should be 15/30x14/29, am I right?

You are absolutely right. I did this problem today and noticed this too. I've noticed that the QR questions of Destroyer need to be answered with an open mind. Some of the permutation/combination problems are also worded very poorly.

 

[jdent]

yeah, I did it yesterday and go tit wrong also but come to think of it i think we are right. Ill find out and post update later.

 

[jdent]

Update my proffesor just got back to me about question 103, and yes we are right. Just understand the following The way the question in #103 is posed is ambiguous (I believe I'd mentioned this in class).

If the numbers are drawn WITH replacement, the answer is 15/30*15/30 = 1/4

If the numbers are drawn WITHOUT replacement, the answer is 15/30*14/29.

Take care!

 

[klutzy1987]

The question is worded poorly. It should read without replacement. You find this type of mistakes often though in math, because wording probability questions clearly can often be a challenge