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

Redeem

Arthimatic Progression...............

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Junior | Next Rank: 30 Posts
Posts: 25
Joined: Thu Aug 05, 2010 3:43 am

Arthimatic Progression...............

by sheelanadh » Wed Aug 11, 2010 10:57 pm
In a flower bed, there are 23 rose plants in the first row, 21 in the second, 19 in the third, and so on. There are

5 rose plants in the last row. How many rows are there in the flower bed?


(a)23
(b)20
(c)7
(d)10


please help me........ how to solve it.....
Top
Source: — Problem Solving |
Legendary Member
Posts: 759
Joined: Mon Apr 26, 2010 10:15 am
Thanked: 85 times
Followed by:3 members

by clock60 » Wed Aug 11, 2010 11:29 pm
23=5+2(n-1)
n=10
Top
Senior | Next Rank: 100 Posts
Posts: 34
Joined: Thu Aug 05, 2010 2:39 am

by likithae » Wed Aug 11, 2010 11:52 pm
clock60 wrote:23=5+2(n-1)
n=10

thank you ....but in the above steps used (n-1) ....can u explain me please..
Top
Legendary Member
Posts: 759
Joined: Mon Apr 26, 2010 10:15 am
Thanked: 85 times
Followed by:3 members

by clock60 » Thu Aug 12, 2010 12:07 am
it is AP
a(n)=a(1)+d(n-1)
Top
Post new topic Post Reply
• Page 1 of 1