Author 
Message 
TAGS:


Moderator
Joined: 18 Apr 2015
Posts: 5202
Followers: 77
Kudos [?]:
1049
[0], given: 4698

How many positive fivedigit integers contain the digit grou [#permalink]
15 Sep 2017, 07:37
Question Stats:
53% (01:27) correct
46% (01:57) wrong based on 13 sessions
How many times does the digit grouping “57” (in that order) appear in all of the fivedigit positive integers? For instance, “57” appears once in 12,357, twice in 57,057, and does not appear in 24,675. (A) 279 (B) 3,000 (C) 3,500 (D) 3,700 (E) 4,000
_________________
Get the 2 FREE GREPrepclub Tests
Last edited by Carcass on 08 Jul 2018, 11:34, edited 1 time in total.
Edited by Carcass




Director
Joined: 03 Sep 2017
Posts: 521
Followers: 1
Kudos [?]:
334
[1]
, given: 66

Re: How many positive fivedigit integers contain the digit grou [#permalink]
18 Sep 2017, 00:59
1
This post received KUDOS
Is there a solution faster than mine?
My idea is to think that these numbers can be of three kinds, given that they are 5digit: YXX57, YX57X or Y57XX, plus the numbers 57XXX. Then, digit Y can be each integer between 1 and 9, thus it can take nine values, whereas the X digit can take any value between 0 and 9, meaning ten values. For one of the first three numbers the possibilities are 9*10*10 = 900, thus for the three number we have a total of 2700 numbers. The numbers 57XXX instead are 10*10*10 = 1000. Summing 2700 and 1000 we get 3700, thus answer D!



Moderator
Joined: 18 Apr 2015
Posts: 5202
Followers: 77
Kudos [?]:
1049
[0], given: 4698

Re: How many positive fivedigit integers contain the digit grou [#permalink]
18 Sep 2017, 06:13
Correct answer. However, in such questions, the shortcut is not too short. It works till some point. Regards
_________________
Get the 2 FREE GREPrepclub Tests



Intern
Joined: 04 May 2017
Posts: 36
Followers: 0
Kudos [?]:
21
[1]
, given: 6

Re: How many positive fivedigit integers contain the digit grou [#permalink]
08 Jul 2018, 02:34
1
This post received KUDOS
This question is wrong worded and Manhattan has issued the errata. Check here https://www.manhattanprep.com/gre/errat ... a5lb2ed/
_________________
Do not pray for an easy life, pray for the strength to endure a difficult one  Bruce Lee



Moderator
Joined: 18 Apr 2015
Posts: 5202
Followers: 77
Kudos [?]:
1049
[0], given: 4698

Re: How many positive fivedigit integers contain the digit grou [#permalink]
08 Jul 2018, 11:34
Thank you so much. Regards
_________________
Get the 2 FREE GREPrepclub Tests




Re: How many positive fivedigit integers contain the digit grou
[#permalink]
08 Jul 2018, 11:34





