If 1+2+3+...+n=n (n+1), then
3 (1+3+5+....+99)=?	Choose the most appropriate option: A) 7000 B) 7250 C) 7500 D) 7750 E) 6750
Explanation :   To solve this use the formula of AP,   Sn= (n/2)(a+l) ................(1)   To find n, use   =&gt; Tn= a+(n-1)d   =&gt; 99=1+(n-1)2   =&gt; n=50   Use value of n in (1)   then,   Sn = (50/2)(1+99) = 2500   Ans:- 3(Sn) = 7500   Answer : 7500
<result>C</result>
If 1+2+3+...+n=n (n+1), then
3 (1+3+5+....+99)=?