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

Redeem

Arithmetic progression

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 43
Joined: Sun Apr 19, 2009 2:02 am
Thanked: 2 times

Arithmetic progression

by T_A_M » Thu May 07, 2009 12:41 pm
Hi
Please can someone help me with this problem.
I know the formula.

a + (n-1) d

In this case a is 23 and d is -3

But what is n?

How do you approach this?
Top
Source: — Problem Solving |
Junior | Next Rank: 30 Posts
Posts: 18
Joined: Tue May 05, 2009 11:03 am

by vitaly » Fri May 08, 2009 7:56 pm
I know the formula, but I don't know what this formula is for :)

Is it to find n-th member of arithmetic progression?

a is the first member
d is the difference between a_i, a_(i-1)

for example
0, 2, 4, 8, 10, ...

a = 0, d = 2
So 5-th member a_5 = a+5d = 10
Top
Post new topic Post Reply
• Page 1 of 1