SOLUTION: The first and the last term of an arithmetic progression are 9 and 93.If the sum of the arithmetic progression is 663,find the number of terms.

Question 935867: The first and the last term of an arithmetic progression are 9 and 93.If the sum of the arithmetic progression is 663,find the number of terms.
Found 2 solutions by mananth, stanbon:
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!

Sn = n/2 (a+l)
a= first term
l = last term
663=n/2(9+93)
663*2 = n(102)
663*2/102= n
=13
Number of terms = 13
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
The first and the last term of an arithmetic progression are 9 and 93.If the sum of the arithmetic progression is 663,find the number of terms.
---
a = 9
a(n) = 9+(n-1)d = 93
----
(n/2)(9+93) 663
------
n*51 = 663
n = 13
-----
Ans:: n = 13
--------------
Cheers,
Stan H.
-----------------
RELATED QUESTIONS
A geometric progression has 6 terms. The first term is 192 and the common ratio is 1.5.... (answered by greenestamps)
A geometric progression has six terms. The first term is 486 and the common ratio is ;.... (answered by greenestamps)
the first and last term of an arithmetic progression are -30 and 10 respectively. find... (answered by tommyt3rd)
The first term of an arithmetic progression is 12 and the sum of the first 16 terms is... (answered by greenestamps)
The first term of an arithmetic progression is -12,and the last term is 40. If the sum of (answered by Fombitz)
A geometric progression and an arithmetic progression have the same first term. The... (answered by htmentor)
The 2nd, 4th and 8th terms of an arithmetic progression are the three consecutive terms... (answered by mananth)
the sum of the first and last terms of an arithmetic progression is 42.the sum of all the (answered by ikleyn)
The first term of an arithmetic progression is 8 and the last term is 34. The sum of the (answered by MathLover1)