+0  
 
0
30
1
avatar

There are 20 terms in an arithmetic sequence. The sum of these terms with odd numbers is equal to 220. The sum of the terms with even numbers is equal to 250. Find the two middle terms of the sequence.

 

Good luck!

 Jul 30, 2020
 #1
avatar
0

Here is one sequence that satisfies all the coditions in your question. And here is the "closed form"  formula that generates each term:
a(n) = 1/2 (4 n + (-1)^n + 5) 
Sum=(4, 7, 8, 11, 12, 15, 16, 19, 20, 23, 24, 27, 28, 31, 32, 35, 36, 39, 40, 43) = 470
The odd-numbered terms sum up to 220, while the even-numbered terms sum up to 250 and the total sum of the sequence is 470.
The two "middle terms" are: 23 and 24
Note: This may not be the sequence that you have, but it is just as valid as any other sequence.

 Jul 31, 2020

23 Online Users

avatar