Question 398543: There are nine balls numbered one through nine. You draw four balls at the same time. What is the probability that the sequence 2,5,7,9 will be drawn? I have tried the counting principle and my answer was .00033 but this is not one of my choices. Please help. Thank you.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! There are nine balls numbered one through nine. You draw four balls at the same time. What is the probability that the sequence 2,5,7,9 will be drawn? I have tried the counting principle and my answer was .00033 but this is not one of my choices.
------------------
2579 is one sequence out of 9*8*7*6 sequences
----
P(2,5,7,9) = 1/3024 = 0.00033
===================================
I get what you got.
Note: The answer book does not always have the right answer.
===================================
By the way we are counting a sequence, which has order.
It may be the problem is looking for the group {2,5,7,9}
which is one group out of 9C4 = 126
----
That probability would be 1/126 = 0.007937..
====================
Cheers,
Stan H.
|
|
|
