Dear Friends,
We shall discuss about Progression(A.P. and G.P.) of the Quant
section. Now a days this topic has
became an important part of the Quant Section in SSC Mains 2015. So Here we will help you in
this.We will provide short notes on
Progression(A.P. and G.P.) with Quant Quiz.
Progression : If a collection of numbers (or quantities) are arranged in
accordance with a fixed rule , then it is called a sequence or a progression .
There are two types of Progression :
1. Arithmetic Progression (A.P): It is a sequence in which the difference
between any two consecutive terms be constant. This constant difference is
called the common difference of the progression and denoted by 'd',
For example,3,7,11,15,19 is an Arithmetic Progression with constant
difference
= 7-3 = 11-7 = 15-11 = 4,and first term = 3
2. Geometric Progression (G.P): It is a sequence in which the ratio of any
term to the just preceding term is a constant This constant ratio is called the
common ratio of the G.P.and is denoted by r.
For example, 4,8,16,32,64 is a in which
First term a = 4 and r = 8/4 = 16/8 =32/16 = 2
Some Questions based on Above Concepts:
1. Find the 13th term of the A.P. 11,17,23.....
(1) 83
(2) 85
(3) 93
(4) 86
2. Find the nth term of the A.P. 5,9,13,17.....
(1) 4n+3
(2) 4n+2
(3) 4n+1
(4) 5n+1
3. How many terms are there in the A.P. given by 15,21,27,....279
(1) 85
(2) 55
(3) 43
(4) 45
4. Which term of the sequence 9,14,19.....is 139?
(1) 22
(2) 25
(3) 27
(4) 29
5. Find the 7th term of the G.P. 4,8,16.....
(1) 256
(2) 156
(3) 254
(4) 264
Answers and Solution:
1.(1) In the given A.P.,
we have a = 11, d = 17-11 = 6
using an = a +(n-1)d, we get
=> a13 = 11 +(13-1)6 => a13 = 83
2.(3) In the given A.P.,
we have a = 5, d = 9-5 = 4
using an = a +(n-1)d, we get
= 5 +(4-1)6
=> an = 4n+1
3.(4) let the A.P.contain n terms, then
we have a = 15, d = 21-15 = 6 an = 279
using an = a +(n-1)d, we get
=>279 = 15 +(n-1)6
=>6n = 270
n = 45
4.(3) The given sequence is an A.P.
with first term a = 9 and common difference = d= 14-9 =5
a = 9
Using, an = a +(n-1)d, we get
=> 139 = 9 +(n-1)5
=> n-1 = 130/5 = 26
=> n = 27
5.(1) In the given G.P.., a = 4,r = 8/4 = 2
Using an = ar^n-1,where n =7
a7 = 4*2^7-1 = 4*2^6 = 256
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