If (k - 3), (2k + 1) and (4k + 3) are three consecutive terms of an A.P., find the value of k.

Find three numbers in A.P., whose sum is 15 and the product is 80.

The angles of triangle are in A.P. whose common difference is 20°. Find angles.

-11, -7, -3, …….,49, 53 are the terms of a progression.

Answer the following:

(a) What is the type of progression?

(b) How many terms are there in all?

(c) Calculate the value of middle most term.