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

The sum of n terms of two A.P.’s are in the ratio 5n + 4 : 9n + 6. Then, the ratio of their 18<sup>th</su…

If a + 1, 2a + 1, 4a - 1 are in A.P., then the value of a is:

What is the sum of the following series? -64, -66, -68, ......, -100

The sum of first five multiples of 3 is:

The n<sup>th</sup> term of an A.P., the sum of whose n terms is S<sub>n</sub>, is

The first three terms of an A.P. respectively are 3y – 1, 3y + 5 and 5y + 1. Then, y equals

Find the 15<sup>th</sup> term of the sequence 20, 15, 10 . . . . .