T is the sum of the first 10 k

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shibal: Master | Next Rank: 500 Posts; Posts: 345; Joined: Wed Mar 18, 2009 6:53 pm; Location: Sao Paulo-Brazil; Thanked: 12 times; GMAT Score:660

by shibal » Thu Jun 25, 2009 6:29 pm

(-1)k+1(½k). T is the sum of the first 10 k, is t:

a. > 2
b. between 1 and 2
c. between ½ and 1
d. between ¼ and ½
e. < ¼

OA: d

Source: Beat The GMAT — Problem Solving | Thu Jun 25, 2009 6:29 pm

pops: Master | Next Rank: 500 Posts; Posts: 148; Joined: Tue Jun 09, 2009 11:06 pm; Thanked: 7 times

by pops » Thu Jun 25, 2009 9:14 pm

I am not able to understand the question. Can you make it clearer please.

shibal: Master | Next Rank: 500 Posts; Posts: 345; Joined: Wed Mar 18, 2009 6:53 pm; Location: Sao Paulo-Brazil; Thanked: 12 times; GMAT Score:660

by shibal » Sat Jun 27, 2009 6:59 am

here it goes....
(-1)^k+1(½k). T is the sum of the first 10 k, is t:

DanaJ: Site Admin; Posts: 2567; Joined: Thu Jan 01, 2009 10:05 am; Thanked: 712 times; Followed by:550 members; GMAT Score:770

by DanaJ » Sat Jun 27, 2009 8:40 am

This is a GMATprep question. Note that all such questions have been discussed before, so doing a quick search of some keywords will surely yield a solution:

https://www.beatthegmat.com/gmat-prep-qu ... 21502.html

https://www.beatthegmat.com/sequence-exp ... 31657.html

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