GRE Prep Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized
for You
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
How many possible combinations can a 3-digit safe code have?
[#permalink]
07 May 2019, 10:09
07 May 2019, 10:09
Expert Reply
00:00
Question Stats:
50% (00:15) correct
50% (00:22) wrong based on 38 sessions
Hide Show timer Statistics
How many possible combinations can a 3-digit safe code have?
(A) \(9C_3\)
(B) \(9P_3\)
(C) \(3^9\)
(D) \(9^3\)
(E) \(10^3\)
(A) \(9C_3\)
(B) \(9P_3\)
(C) \(3^9\)
(D) \(9^3\)
(E) \(10^3\)
Re: How many possible combinations can a 3-digit safe code have?
[#permalink]
09 May 2019, 00:38
09 May 2019, 00:38
1
Bookmarks
Could it be 10C3?
Re: How many possible combinations can a 3-digit safe code have?
[#permalink]
10 May 2019, 02:52
10 May 2019, 02:52
Expert Reply
The safe combination could be 433 or 334; the combinations are the same, but their ordering is different.
Order is important for the safe combinations, this is a permutation problem.
A safe code can be made of any of the numbers {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}. No two objects in the set are indistinguishable. Hence, the base set does not have any indistinguishable objects.Repetitions of numbers in the safe code are possible. For example, 334 is a possible safe code.
Hence, the problem is a permutation, with repetition and no indistinguishable objects.
Moreover, the first digit has an additional rule: it cannot be 0 (because in this case the number would actually be 2-digit number).
Hope this helps.
Regards
Order is important for the safe combinations, this is a permutation problem.
A safe code can be made of any of the numbers {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}. No two objects in the set are indistinguishable. Hence, the base set does not have any indistinguishable objects.Repetitions of numbers in the safe code are possible. For example, 334 is a possible safe code.
Hence, the problem is a permutation, with repetition and no indistinguishable objects.
Moreover, the first digit has an additional rule: it cannot be 0 (because in this case the number would actually be 2-digit number).
Hope this helps.
Regards
