Without adding, find the sum
(i) 1+3+5+7+9
(ii) 1+3+5+7+9+11+13+15+17+19
(iii) 1+3+5+7+9+11+13+15+17+19+21+23

see full answer

21% of IItians & 23% of AIIMS delhi doctors are from Sri Chaitanya institute !!

An Intiative by Sri Chaitanya

25, 100 and 144

20, 80 and 99

35, 30 and 33

45, 40 and 44

answer is A.

(Unlock A.I Detailed Solution for FREE)

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Detailed Solution

In the first part we have,
1+3+5+7+9
These are first consecutive odd terms. Now we know that the sum of first n consecutive n terms =

= n^{2}

So, the sum of these 5 first consecutive odd terms,

= 5^{2}

= 25

Now, in the second part we have,
1+3+5+7+9+11+13+15+17+19
So, the sum of these 10 first consecutive odd terms,

= 10^{2}

= 100

In the third part we have,
1+3+5+7+9+11+13+15+17+19+21+23
So, the sum of these 12 first consecutive odd terms,

= 12^{2}

= 144

So, the required sum is 25, 100 and 144.
Option 1 is correct.

Watch 3-min video & get full concept clarity