Online Aptitude

Welcome to Placement papers and jobs help portal. Here you can find previous placement questions, sample placement papers, job interview questions and other material pertaining to top Indian companies like Infosys, Wipro, HCL, Satyam, TCS, HCL, HP, Accenture etc.
We are constantly striving to provide you the latest job openings and placement papers and services available from India.

If each term of a series differs from its preceding term by a constant, then such a progression is called arithmetic progression.

e.g: 2,5,8,11

In the above sequence the difference between any two terms in 3.

Formula

Consider an AP : a, (a + d), (a + 2d), (a + 3d),(a + 4d),....

n th term of the above sequence = Tn = a + (n - 1)d

Sum to n no of terms S_n = n / 2 (2a + (n - 1)d)

Another formula for S_n = n / 2 (first term + last term)

Any progression or sequence with successive terms having a common ration is called geometric progression.

e.g: 2,4,8,16...

In the above sequence the common ratio is 2 for any two successive terms

Formula

Consider a GP - a, ar, ar².... where a is the first term and r is the common ratio

n th term, T_n = ar^n-1

Sum to n terms , S_n = a(1 - rⁿ)/(1-r)

In case r lies beween -1 and +1 then Sum of all terms of the series = a/(1 - r)