Three number are in $A.P.$ such that their sum is $18$ and sum of their squares is $158$. The greatest number among them is
$10$
$11$
$12$
None of these
The number of terms in the series $101 + 99 + 97 + ..... + 47$ is
If $a,b,c$ are in $A.P.$, then $\frac{1}{{\sqrt a + \sqrt b }},\,\frac{1}{{\sqrt a + \sqrt c }},$ $\frac{1}{{\sqrt b + \sqrt c }}$ are in
The sums of $n$ terms of three $A.P.'s$ whose first term is $1$ and common differences are $1, 2, 3$ are ${S_1},\;{S_2},\;{S_3}$ respectively. The true relation is
The difference between any two consecutive interior angles of a polygon is $5^{\circ}$ If the smallest angle is $120^{\circ},$ find the number of the sides of the polygon.
Find the sum of all numbers between $200$ and $400$ which are divisible by $7.$