Sigma n3

Q. Sum to n terms of the series $\frac{1^3}{1}+\frac{1^3+2^3}{1+3}+\frac{1^3+2^3+3^3}{1+3+5}+.....$ is

1. $\frac{n}{24}(n^2+11n+12)$
2. $\frac{n}{24}(2n^2+9n+13)$
3. $\frac{n}{24}(n^2+9n+14)$
4. $\frac{n}{24}(2n^2+7n+15)$

Q. If the mean of first $n$ odd natural numbers is $\frac{n^2}{81}$ =, then $n$ is equal to

1. $9$
2. $81$
3. $27$
4. none of these

Q. The sum of first 9 terms of the series.
$\frac{1^3}{1}+\frac{1^3+2^3}{1+3}+\frac{1^3+2^3+3^3}{1+3+5}+...$

1. 142
2. 192
3. 71
4. 96