Question

find the sum of all the odd integers between 100 and 700
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Answer 1

Answer:

Sn = 120000

Step-by-step explanation:

First we need to find the number of add numbers between 100 and 700

first odd no. is 101,103,105.... 699

A1 = 101, An = 699

common diff = d = 2

So A1 + (n-1)2 = An

101 + (n-1)2 = 699

(n-1) = (699-101)/2 = 299

n = 300

Now to calculate the sum of odd nos:

$sn = \frac{n}{2} (2a + (n - 1)d)$

a = 101 n = 300 d = 2

Sn = 300/2[ 2(101) + (300-1).2]

Sn = 150(202 + 598)

Sn = 150(800)

Sn = 120000