GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 16 Sep 2019, 09:53

### GMAT 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

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# 'A' is the set of the first 100 positive integers. What is the minimum

Author Message
TAGS:

### Hide Tags

Manager
Joined: 23 Apr 2019
Posts: 214
'A' is the set of the first 100 positive integers. What is the minimum  [#permalink]

### Show Tags

21 Aug 2019, 10:36
4
00:00

Difficulty:

75% (hard)

Question Stats:

33% (02:10) correct 67% (01:26) wrong based on 46 sessions

### HideShow timer Statistics

'A' is the set of the first 100 positive integers. What is the minimum number of elements that should be picked from 'A' to ensure that at least one pair of numbers whose difference is 10 is picked?

(A) 11

(B) 20

(C) 51

(D) 55

(E) 60
Director
Status: Manager
Joined: 27 Oct 2018
Posts: 602
Location: Egypt
GPA: 3.67
WE: Pharmaceuticals (Health Care)
Re: 'A' is the set of the first 100 positive integers. What is the minimum  [#permalink]

### Show Tags

22 Aug 2019, 17:28
by picking the first 9 numbers (1-9), we have to skip the following 9 (10-19)
then pick (20-29), skip (30-39), pick (40-49), skip (50-59), pick (60-69), skip (70-79), pick (80-89), skip (90-99), pick (100)

so the number of picked ones = 9+10+10+10+10+1 = 50
by picking any further number (51th), its difference from at least another number must be 10
_________________
Thanks for KUDOS
Re: 'A' is the set of the first 100 positive integers. What is the minimum   [#permalink] 22 Aug 2019, 17:28
Display posts from previous: Sort by