J P Mohindru and Bharat Mohindru Solutions for Chapter: Arithmetic Progressions, Exercise 8: COMPETITION FILE

Two A.P.s have the same common difference. The first term of one of these is $-1$ and that of the other is $-8$. Then the difference between their $4^{\mathrm{th}}$ terms is

If $7$ times the $7^{\mathrm{th}}$ term of an A.P. is equal to $11$ times its ${11}^{\mathrm{th}}$ term, then its ${18}^{\mathrm{th}}$ term will be:

The $4^{\mathrm{th}}$ term from the end of the A.P., $-11,$ $-8,$ $-5,$ ....$,49$ is

The famous mathematician associated with finding the sum of the first $100$ natural numbers is

If the first term of an A.P. is $-5$ and the common difference is $2$, then the sum of the first $6$ terms is: 

The sum of first $16$ terms of the A.P.: $10$, $6$, $2$, ... is: 

In an A.P., if $a=1,$ $a_n=20$ and $S_n=399,$ then $n$ is

The sum of first five multiples of $3$ is