SOLUTION: Average integers between 25 41

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Question 988859:
Average integers between 25 41
Found 2 solutions by Shai, Edwin McCravy:
Answer by Shai(25) About Me  (Show Source):
You can put this solution on YOUR website!
The series here is 25+26+27+...41
Since the given series is in arithmetic
Progression we need to first find n
Either using n2-n1+1 i.e(41-25+1)=17 or
Using the formula n2=n1+(n-1)d where d is
The distance between the consecutive numbers
I.e 1..using this u get n=17
Now using the formula sum=(n/2)(n1+(n-1)d)
We get the value as 561

Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
The integers between 25 and 41 are 26,27,...,40

The average of any string of equally spaced numbers is
the same as the average of the first and last numbers.

Integers are all equally spaced so we just average the
first and last: %2826%2B40%29%2F2=66%2F2=33

Checking:

 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
+40
495

    33
15)495
   45
    45
    45
     0

Edwin