Question

14) Find the sum of two Gigit odd numbers. ( )​

Answer 1

All two digit odd numbers are 11, 13, 15, 17,...99, which are in A.P with a1=11, an(last term)=99, and d=2.

Let the number of terms be 'n'.

a+(n-1)d=99

11+(n-1)2=99

11+2n-2=99

2n+9=90

2n=99-9

2n=90

n=90/2

n=45

Sum of n terms when number of terms, first term and last term are given is,

Sn=n/2[a1+an]

=45/2[11+99]

=45/2×110

=2475

Therefore, the sum of all two digit odd positive numbers are 2475.

HOPE IT HELPS YOU DEAR.......

WITH LOVE, ARCHANA:-)

Answer 2

Answer:

2,475

11+13+15+17+19+21+23+25

+27+29+31+33+35+37+39+41

+43+45+47+49+51+53+55+57

+59+61+63+65+67+69+71+73

+75+77+79+81+83+85+87+89+91

+93+95+97+99=2,475