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![For all real numbers, [x] = the greatest integer less than or equal to](/forum/styles/gmatclub_light/imageset/icon_post_target_unread.svg "For all real numbers, [x] = the greatest integer less than or equal to"){kind=icon}
10 Jun 2019, 00:28
Kudos
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E
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Difficulty:
55%
(hard)
Question Stats:
70% (02:25) correct
30%
(02:34)
wrong
based on 702
sessions
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For all real numbers, [x] = the greatest integer less than or equal to x.
What is the sum of the 28 terms in the series [1/6] + [2/6] + [3/6] + … + [28/6]?
A. 48
B. 50
C. 52
D. 54
E. 56
What is the sum of the 28 terms in the series [1/6] + [2/6] + [3/6] + … + [28/6]?
A. 48
B. 50
C. 52
D. 54
E. 56
Write a general form of the terms =[n/6], where n is an integer
when 1≤n≤5, [n/6]=0
when 6≤n≤11, [n/6]=1
when 12≤n≤17, [n/6]=2
when 18≤n≤23, [n/6]=3
when 24≤n≤28, [n/6]=4
[1/6] + [2/6] + [3/6] + … + [28/6]= 0*5 + 1*6 + 2*6 + 3*6 + 4*5 = 56
when 1≤n≤5, [n/6]=0
when 6≤n≤11, [n/6]=1
when 12≤n≤17, [n/6]=2
when 18≤n≤23, [n/6]=3
when 24≤n≤28, [n/6]=4
[1/6] + [2/6] + [3/6] + … + [28/6]= 0*5 + 1*6 + 2*6 + 3*6 + 4*5 = 56
Bunuel
Archit3110
10 Jun 2019, 08:52
Kudos
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Bunuel
need to be careful with the given function [x] = the greatest integer less than or equal to x
so sum of 28 terms ; [1/6] + [2/6] + [3/6] + … + [28/6]
from 1/6 to 5/6; [x]=0
6/6 to 11/6 ; [x]=1
12/6 to 17/6; 2
18/6 to 23/6 ; 3
24/6 to 28/6 ; 4
so total sum ; 0*6+1*6+2*6+3*6+4*5 ; 56
IMO E
