# Foo - Not sure what this statistics question is asking

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phantomcow2
02-02-09, 10:29 PM
A homework problem from my textbook:
A financial analyst was asked to evaluate earnings prospects for seven corporations over the next year and to rank them in order of predicted growth rates.
How many different rankings are possible?

I know that the answer is 5040. How does this make sense? When they say "over the next year," is the analyst recording daily activity? Can somebody provide some insight here?

alpacalypse
02-02-09, 10:36 PM
It's a permutation problem. You have 7 items, and the question is asking how many different ways they can be ordered. The number of possible permutations (orderings) is the factorial of the number of items: 7! = 7 * 6 * 5 * 4 * 3 * 2 * 1 = 5040.

phantomcow2
02-02-09, 10:43 PM
I see that it is a permutations problem now. What I don't fully understand is what exactly is being ordered?

valygrl
02-02-09, 10:53 PM
It's irrelevant what is being ordered or how the values are assigned. The question is just asking how many ways they can be ranked.

phantomcow2
02-02-09, 11:03 PM
Brain fart :/ I feel like I am unable to comprehend statistics problems right now.

FlowerBlossom
02-02-09, 11:09 PM
This isn't statistics. Does that make you feel better? :)

But, you need these kinds of processes to understand populations, which is what statistics is about.

alpacalypse
02-02-09, 11:10 PM
The companies' projected growths are being ordered, but that doesn't matter for the question-- it's just asking how many different ways they could be ordered.