Progressions

grkmurthy · Senior Consultant Joined: 14 Oct 2007 Posts: 37

If a, b, c are in Arithmetic Progression, what will be the sequence of ab, ac, bc?

(1) Arithmetic Progression
(2) Geometric Progression
(3) Harmonic Progression
(4) Arithmetico - Geometric sequence
(5) none of the above

ksvickram · Senior Consultant Joined: 02 Jan 2008 Posts: 29

Let us take for example, the numbers in AP to be 1,2 and 3

ab = 2
ac = 3
bc = 6

The sequence = 2,3,6 ==> Is a combination of Arithmetic and Geo series.

Let s see this: 2 + 2 * ( 1/2) = 3
3 + 3 * (2 / 2) = 6 and So on..... A bit tricky one. but was able to deduce with sub of two values, 1,2,3 and 2,4,6. it works for both the seq. Try if you want.

Post me if you have any other shorter methods..... Smile