If the sum of $1 + \frac{1 + 2}{2} + \frac{1 + 2 + 3}{3} + \dots$ to $n$ terms is $S$,then $S$ is equal to

Let $a_1, a_2, \dots, a_{10}$ be in $A.P.$ and $h_1, h_2, \dots, h_{10}$ be in $H.P.$ If $a_1 = h_1 = 2$ and $a_{10} = h_{10} = 3$,then $a_4 h_7$ is

If all interior angles of a quadrilateral are in an $A.P.$ and the common difference is $10^{\circ}$,find the smallest angle. (in $^{\circ}$)

Maximum value of the sum of the Arithmetic Progression $50, 48, 46, 44, \dots$ is

Let $\frac{1}{x_1}, \frac{1}{x_2}, \frac{1}{x_3}, \dots, \frac{1}{x_n}$ ($x_i \neq 0$ for $i = 1, 2, \dots, n$) be in $A.P.$ such that $x_1 = 4$ and $x_{21} = 20$. If $n$ is the least positive integer for which $x_n > 50$,then $\sum_{i=1}^n \frac{1}{x_i}$ is equal to:

If the $10^{\text{th}}$ term of an $A$.$P$. is $\frac{1}{20}$ and its $20^{\text{th}}$ term is $\frac{1}{10}$,then the sum of its first $200$ terms is