Arithmetic Prog...

If $$n^{th}$$ term of an AP is  $$\dfrac {1}{3}(2n+1)$$, then the sum of its $$19$$ term is

Find the common difference of an AP. whose first term is $$100$$ and the sum of whose first six terms is five times the sum of the next six terms.

Which term of AP : $$3, 15, 27, 39,..$$ will be $$132$$ more than its $$54th$$ term?

The sum of the first nineteen terms of an A.P. $$a_1,\, a_2,\, a_3$$ .......... if it is known that $$a_4\, +\, a_8\, +\, a_{12}\, +\, a_{16}\, =\, 224$$ is .......... .

If $$9^{th}$$ and $$19^{th}$$ terms of an AP are $$35$$ and $$75$$, then its  $$20^{th}$$ term is

The sum of all integers between $$81$$ and $$719$$ which are divisible by $$5$$ is

The value of $$1 + 3 + 5 + 7 + 9 + ............. + 25$$ is:

The sum of $$3^{rd}$$ and $$15^{th}$$ elements of an arithmetic progression is equal to the sum of $$6^{th},\, 11^{th}\, and\, 13^{th}$$ elements of the same progression. Then which element of the series should necessarily be equal to zero?

Ramkali saved $$Rs. 5$$ in the first week of a year and then increased her weekly savings by $$Rs. 1.75.$$ If in the nth week, her weekly savings become $$Rs. 20.75,$$ find $$n.$$

The sum of first $$n$$ terms of the $$A.P$$.  $$\sqrt{2}\, +\, \sqrt{8}\, +\, \sqrt{18}\, +\, \sqrt{32}\, +\, ........$$ is ......