Question

The sum of 100+111+___+199 is

Answer 1

HI FRND!

Answer:

This can be taken as an AP:100+111+_____+199

Step-by-step explanation:

In this AP;

a=100

an=199

And,

d=111-100=11

Now the sum;

s=n/2(2a+(n-1)d)

s=n/2(2*100+(n-1)11)                           ..............(i)

and here n is not known to us so we will first find n.

as we know

an=a+(n-1)d

199=100+(n-1)11

= 199=100+11n-11

= 199=89+11n

= 199-89=11n

= 110=11n

= 110/11=n

therefore;

n=10

now substituting the value of n in (i)

s=10/2(2*100+(10-1)11)

= 5(200+9*11)

= 5(200+99)

= 5(299)

s=1495

Therefore, the sum of the given numbers is 1495.

HOPE IT HELPS!

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