SOLUTION: In the sequence 3,8,13,18, what term of the series is the number 2218?

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Question 255435: In the sequence 3,8,13,18, what term of the series is the number 2218?
Found 2 solutions by Edwin McCravy, Fombitz:
Answer by Edwin McCravy(20055) About Me  (Show Source):
You can put this solution on YOUR website!
In the sequence 3,8,13,18, what term of the series is the number 2218?

This is a sequence (not "series" unless they are
added together, with + signs between).

Note that the 2nd term - 1st term = 8-3 = 5

Note that the 3rd term - 2nd term = 13-8 = 5

Note that the 4th term - erd term = 18-13 = 5

That tells us that this is an arithmetic sequence 
with common difference, d=5.

The formula for the nth term a%5Bn%5D of an arithmetic
sequence is

a%5Bn%5D=a%5B1%5D%2B%28n-1%29%2Ad

2218=3+%2B+%28n-1%29%2A5

2215=5%28n-1%29

Divide both side by 5

443=n-1

444=n

So a%5B444%5D=2218, the 444th term.

Edwin

Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
1.3%2B5=8
2.8%2B5=3%2B5%2B5=3%2B%285%292=13
3.13%2B5=8%2B5%2B5=3%2B%285%293=18
3%2B5n=2218
5n=2215
n=443
2218 is the 443rd term.