Verbal Reasoning - Series Completion - Discussion
Discussion Forum : Series Completion - Section 1 (Q.No. 4)
Directions to Solve
Choose the correct alternative that will continue the same pattern and replace the question mark in the given series.
4.
In the series 2, 6, 18, 54, ...... what will be the 8th term ?
Answer: Option
Explanation:
Clearly, 2 x 3 = 6, 6 x 3 = 18, 18 x 3 = 54,.....
So, the series is a G.P. in which a = 2, r = 3.
Therefore 8th term = ar8-1 = ar7 = 2 x 37 = (2 x 2187) = 4374.
Discussion:
27 comments Page 1 of 3.
Prem said:
1 decade ago
We have to go with formula only ?
Aman said:
1 decade ago
Not understandable.
Kanna said:
1 decade ago
If we don't know formula we can go in simple logic
2,6,18,54,5th term,6th term,7th term,8th term(here we should get answeer)
So
2 x 3 = 6,
6 x 3 = 18,
18 x 3 = 54,
54 x 3=162(5th term),
162 x 3=486(6th term),
486 x 3=1458(7th term),
1458 x 3=4374(8th term and our answer)
2,6,18,54,5th term,6th term,7th term,8th term(here we should get answeer)
So
2 x 3 = 6,
6 x 3 = 18,
18 x 3 = 54,
54 x 3=162(5th term),
162 x 3=486(6th term),
486 x 3=1458(7th term),
1458 x 3=4374(8th term and our answer)
Appy said:
1 decade ago
How do we find 3^7 without using " calculator and multiplying 3 seven times " ? please tell me the easy method to find out a number raised to a large power.
Bhumika said:
1 decade ago
I dont understand the answer.2,6,18,54,5th term,6th term,7th term,8th term(here we should get answeer) .how it comes 4374
Aswini said:
1 decade ago
What does GP mean?can anyone explain me please.
(1)
Avinash Wadhe said:
1 decade ago
GP means Geometric Progression formula.
Sahiba said:
1 decade ago
Geometric progression is one where a set of numbers vary with one number which is multiplied to each one to get the next term.
Ex:2(2*3) = 6(6*3) = 18....
So now 2 6 18... are in gp differing by 3 each.
Ex:2(2*3) = 6(6*3) = 18....
So now 2 6 18... are in gp differing by 3 each.
Arif said:
1 decade ago
There should be some easy method to solve this, Can any one have?
Biji said:
1 decade ago
A = 2.
R = 3.
N = 8 th term.
= 2*3^(8-1).
= 2*3^7.
= 2(3^7) = 2(3^2 * 3^2 * 3^2 * 3).
= 2(9*9*9*3) = 2(81*27).
= 2(2187) = 4374.
3^7 = 3 square * 3 Square * 3 Square * 3.
R = 3.
N = 8 th term.
= 2*3^(8-1).
= 2*3^7.
= 2(3^7) = 2(3^2 * 3^2 * 3^2 * 3).
= 2(9*9*9*3) = 2(81*27).
= 2(2187) = 4374.
3^7 = 3 square * 3 Square * 3 Square * 3.
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