BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Number Properties

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Legendary Member
Posts: 869
Joined: Wed Aug 26, 2009 3:49 pm
Location: California
Thanked: 13 times
Followed by:3 members

Number Properties

by heshamelaziry » Fri Jan 08, 2010 9:25 am
The sum of the first 100 positive integers is 5,050. What is the sum of the first 200 positive integers?

(A) 10,100
(B) 10,200
(C) 15,050
(D) 20,050
(E) 20,100
Top
Source: — Problem Solving |
Newbie | Next Rank: 10 Posts
Posts: 5
Joined: Tue Nov 03, 2009 6:54 am

by mahendra700 » Fri Jan 08, 2010 9:38 am
heshamelaziry wrote:The sum of the first 100 positive integers is 5,050. What is the sum of the first 200 positive integers?

(A) 10,100
(B) 10,200
(C) 15,050
(D) 20,050
(E) 20,100

The formula for sum of first 200 positive integers is n(n+1)/2

==> 200*201/2= 20,100

Hence E is the answer
Top
Master | Next Rank: 500 Posts
Posts: 392
Joined: Thu Jan 15, 2009 12:52 pm
Location: New Jersey
Thanked: 76 times

by truplayer256 » Fri Jan 08, 2010 12:58 pm
Notice that the sum of the first 200 positive integers is...

5050+100+1+100+2+100+3....100+100

=5050+100(100)+5050=20100

E
Top
Post new topic Post Reply
• Page 1 of 1