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Re: permutations & Combinations [#permalink]
same type of question where order doesn't matter

Five people are running in a race. The first three to finish win
gift certificates. How many different groups of people could
win the gift certificates?
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Re: permutations & Combinations [#permalink]
Here it's 5C3 = 5!/3!2!
= 5*4/2 = 10

The idea is to pick a group of 3 people out of 5.
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Re: Five people are running in a race. The first one to finish [#permalink]
hey all,
whats the answer?

i got it as 60 . is that wrong ?
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Re: Five people are running in a race. The first one to finish [#permalink]
Bunuel wrote:
pappueshwar wrote:
hey all,
whats the answer?

i got it as 60 . is that wrong ?


OA is given under the spoiler in the initial post.

Five people are running in a race. The first one to finish wins a gold medal, the second wins a silver medal and the third wins a bronze medal. How many different arrangements of medal winners, in order from first to third, are possible?
A. 5
B. 10
C. 60
D. 120
E. 125

\(C^3_5*3!=60\), where \(C^3_5\) is ways to select the group of 3 winners out of 5 contestants and 3! is ways to arranging them (alternately you can just do \(P^3_5=60\)).

Answer: C.

Hope it helps.



Hello Bunuel,

I didn't understand why you used \(P^3_5=60\) to solve this question. Also, the actual evaluation of it seems to get me - I know this is a silly point but I still get it wrong -

I evaluate as follows:

\(P^3_5\)= 5!/3! = 5*4*3*2*1/ 3*2*1 = 20. where am I going wrong?
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Re: Five people are running in a race. The first one to finish [#permalink]
Expert Reply
SaraLotfy wrote:
Bunuel wrote:
pappueshwar wrote:
hey all,
whats the answer?

i got it as 60 . is that wrong ?


OA is given under the spoiler in the initial post.

Five people are running in a race. The first one to finish wins a gold medal, the second wins a silver medal and the third wins a bronze medal. How many different arrangements of medal winners, in order from first to third, are possible?
A. 5
B. 10
C. 60
D. 120
E. 125

\(C^3_5*3!=60\), where \(C^3_5\) is ways to select the group of 3 winners out of 5 contestants and 3! is ways to arranging them (alternately you can just do \(P^3_5=60\)).

Answer: C.

Hope it helps.



Hello Bunuel,

I didn't understand why you used \(P^3_5=60\) to solve this question. Also, the actual evaluation of it seems to get me - I know this is a silly point but I still get it wrong -

I evaluate as follows:

\(P^3_5\)= 5!/3! = 5*4*3*2*1/ 3*2*1 = 20. where am I going wrong?


First of all \(P^n_k=\frac{n!}{(n-k)!}\), thus \(P^3_5=5!/(5-3)!=60\).

Next, consider the runners to be A, B, C, D and E.

\(P^3_5\) gives all different ordered triplets from 5:
ABC
ACB
BAC
BCA
CAB
CBA

ABD
ADB
BAD
BDA
DAB
DBA
...

Hope it helps.
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Re: Five people are running in a race. The first one to finish [#permalink]
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Re: Five people are running in a race. The first one to finish [#permalink]
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