Question

10. There are 50 competitors in the men’ s ski jumping. 30 move on to the qualifying round.
How many different ways can the qualifying round be selected?

Answer 1

The choices are:

a) 50!
b) 30!
c) 80
d) 1500
e.) 1.25 * 10^(46)

Answer 2

I got e), 1.25 * 10^(46) since the answer should be P(50,30). I just need a confirmation. Thanks.

Answer 3

@Luis_Rivera @Callisto @Hero @TuringTest @mathslover

Answer 4

By "different ways" I believe what they are suggesting is not that each "different way" needs to give us a different set of qualifiers but instead a different permutation of the set of qualifiers.

Also since this is a M/C question, it is clear to see that none of the choices make any sense.

Answer 5

The only one that makes sense is e), the rest seem to be just "obvious" mistakes someone could make.

Answer 6

Anyone agrees with my answer???

Answer 7

@whpalmer4

Answer 8

@whpalmer4 wherere areee uuuuuuuuuuuuuuuuuuuuuuuuuu

Answer 9

@whpalmer4 palmy where are u.

Answer 10

@RadEn You get same answer as me?

Answer 11

hmmm...
it should 50C30, doesnt it ?

Answer 12

Ya that's what I got too. I just wanted to confirm whether others get the same answer as me/agree with my answer.

Answer 13

Wait no, why would it be 50C30

Answer 14

From the way the question is worded, it wouldn't be "unique group of qualifiers". It would be just the many ORDERS of choosing a qualifying round. That's how I interpreted it. Plus, look at the choices. If this was a combinatorics problem, the choices wouldn't be like that. Also, like I mentioned earlier, another way to confirm that the way I'm interpreting the question is correct and that 50P30 is in fact the right answer is by looking at the first 4 choices. Neither of them make any sense which would make the last choice e) the most appropriate answer. Which is what I got. You know what I'm saying? @RadEn

Answer 15

as long as my known, if we want choice r distinct elements from n elements, so just use the combination. note : You use Permutation when order matters. You uce Combination when it doesn't.

Answer 16

@RadEn I know. Here the question is worded in such a way that suggests that order in fact matters which is why you do 50P30 instead of 50C30. This answer would also make sense because the rest of the choices are absolutely senseless.

Answer 17

yeah, i see it... sometimes the option would helps us :)

Answer 18

if me, i want choice f) 50C30
hahaha

Answer 19

I'm sort of an amateur at this, but I'm curious to know why it wouldn't be 30! 50 doesn't matter at all. Only the 30 that moved on to the qualifying round. The remaining 20 didn't make it.

Answer 20

@RadEn, don't run away, weigh in. I want to get your input on it.

Answer 21

You too @genius12. Explain your reasoning behind your answer choice.

Answer 22

actually, this is a combination problem. that's my transleting problem on this case

Answer 23

Yes, what is your reasoning that leads you to believe that is the case?

Answer 24

The reason for why I picked 50P30 is because there is 30 people who are to qualify from 50 correct? So for the first qualifier from the 30, there is 50 choices, for the second there is 49...all the way till the 30th qualifier for whom there is 31 choices.

Doing the multiplication we get:\[\bf \prod_{n=31}^{50}x=31 \times 32 \times 33....\times 50=\ _{50}P_{30}=1.25 \times 10^{46}\]This is the value of all the permutations of how the qualifying round can be selected meaning the order in which it could be selected. @Hero

Answer 25

The 30 have already moved on to the qualifying round. The remaining 20 don't even factor into the equation anymore.

Answer 26

@Hero Where are you getting that from?

Answer 27

We'll have to get more people in on this, but I'm confident that I'm correct.

Answer 28

but thats not exactly 1.25 x 10^46
50P30 = 1.2501158328406120.... x 10^46

Answer 29

Maybe you two are right and maybe I'm just mis-interpreting. I think it's kind of dumb question.

Answer 30

The whole meaning of 50P30 is how many ways can 50 things be arranged in to a group of 30. So if I have numbers set A = {1,2,3..,50}, how many subsets B could I make such that B is a subset of A and has 30 elements and each subset is considering unique if the order of the elements is different.

Answer 31

@RadEn I think they would run out of space to right that much on the test sheet which is why they took it to 2 decimal places.

Answer 32

yeah, maybe

Answer 33

But using some common sense, do we agree that none of a,b,c,d could be the answers? @RadEn

Answer 34

ah i see now..
where there is a competition, must be a winner as rank 1,2,3,4,5,6,...,30.
obviously, the order must be concidered. yes it is permutation not combination. i agree with you, @genius12

Answer 35

:D

Answer 36

It's still awkwardly worded question. The appropriate way to ask the question is to say:

There are 50 competitors in the men’ s ski jumping. 30 will eventually move on to the qualifying round.
How many different ways can the qualifying round be selected?

Answer 37

Now I have a quick question. There is a question I have to draw a tree diagram for. Here is the question:

A dice is rolled. A card is drawn from a deck of face cards (i.e. only Jack,
Queen, King of each suit). A coin is flipped.

a) Draw a tree diagram to define the sample space for this game.

Here is the tree diagram I drew, it's attached as a file. Can you guys look at it and tell me what you think of it?

Answer 38

@genius12, I barely had a chance to get my post responded to.

Answer 39

@Hero Sorry hero but what was your question?

Answer 40

It's not that difficult to figure out what my gripe is.

Answer 41

@Hero Can you say exactly what you're asking instead of using metaphorical speech? I really don't know what your saying when you type "gripe" lol.

Answer 42

I posted something right before you posted your "Quick Question" post. You didn't see my post because it posted microseconds before yours did.

Answer 43

Oh are you referring to the post in which you typed up the reworded question? @Hero

Answer 44

Yes

Answer 45

what about it

Answer 46

Like that post isn't interrogative in any way. It simply rewords the question I asked with the addition of the word 'eventually'.

Answer 47

The eventually is an important word to mention because it alerts to us that we need to consider the 50.

Answer 48

How? Frankly, the eventually makes no difference.

Answer 49

Of course it doesn't from your point of view.

Answer 50

But I think I get it now. The word "selected" is the key word here.

Answer 51

Ya, and another keyword is "Competitors". It tells us that this in fact is a competition which implies that the qualifiers will be ranked which implies that the order of the qualifiers matters.

Answer 52

I already knew it was a Permutation. That was never in question from my point of view.

Answer 53

I see lol. You were questioning about something I didn't get bothered by and I was asking about something you already knew. We have interesting perspectives/point of views.

Answer 54

But I believe the problem is solved and it's all good. Time to close the question. Any more questions/comments?

Answer 55

Nope, it is over.

Answer 56

Nice talking to you. Bye. @Hero @RadEn