If four numbers in A.P. are such that their sum is 50 and the greatest number is 4 times the least, then the numbers are

If the sums of n terms of two arithmetic progressions are in the ration $$\frac{{3n + 5}}{{5n + 7}},$$   then t…

The common difference of an A.P., the sum of whose n terms is S<sub>n</sub>, is

How many 2-digit positive integers are divisible by 4 or 9?

What is the sum of the first 9 terms of an arithmetic progression if the first term is 7 and last term is 55?

What is the sum of the first 12 terms of an arithmetic progression if the first term is -19 and last term is 36?

If the sum of n terms of an A.P. is 3n<sup>2</sup> + 5n then which of its terms is 164 ?

The sum of first n odd natural numbers in