



 
Leigh, Consider the way that Gauss showed us how to sum an arithmetic sequence. You can see an example in our response to a previous question. Your example is an arithmetic sequence so there is some number d that you add to each term to obtain the next term. The middle term of a 15 term sequence is 92 so this is the 8^{th} term. The last term is 7 terms further along in the sequence so it is 92 + 7d. Likewise the first term is 7 terms before the 8^{th} term so it is 92  7d. Thus the sum of the first and last term is 92  7d + 92 + 7d = 92 + 92 = 184. Can you now use Gauss' technique to find the sum of the sequence? Penny  


Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences. 