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 2 of 3.
Nrusingha acharya said:
10 years ago
An other method: 2.
6*3^0.
6*3^1.
6*3^2.
6*3^3.
6*3^4.
6*3^5.
6*3^6,
Only calculate the 8th one not all and get the result.
6*3^0.
6*3^1.
6*3^2.
6*3^3.
6*3^4.
6*3^5.
6*3^6,
Only calculate the 8th one not all and get the result.
Upender Singh Rajput said:
1 decade ago
Solving with GP. (Geometrical Progression) find 8th term.
Now Series is 2 6 18 54.....8th term.
So a =2, r=6\2=3, T8=2(3)7, T8 = 4374.
Now Series is 2 6 18 54.....8th term.
So a =2, r=6\2=3, T8=2(3)7, T8 = 4374.
Kanhay said:
1 decade ago
A means first term and are means common ratio.
(1)
Chiran said:
1 decade ago
What is the meaning of a and r please explain me?
Sangeeta said:
1 decade ago
This series is in geometric progression:
So 8th term is = 2*3^(8-1).
= 2*3^(7).
= 2*3^(4+3).
= 2*[3^4*3^3].
= 2*[81*27].
= 2*2187.
= 4374.
So 8th term is = 2*3^(8-1).
= 2*3^(7).
= 2*3^(4+3).
= 2*[3^4*3^3].
= 2*[81*27].
= 2*2187.
= 4374.
Manjot singh said:
1 decade ago
2*3 = 6.
6*3 = 18.
18*3 = 54.
54*3 = 162.
162*3 = 486.
486*3 = 1458.
1458*3 = 4374.
6*3 = 18.
18*3 = 54.
54*3 = 162.
162*3 = 486.
486*3 = 1458.
1458*3 = 4374.
Sameer said:
1 decade ago
@Kanna.
Why we need to multiply with 3 With Given Numbers?
Why we need to multiply with 3 With Given Numbers?
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.
Arif said:
1 decade ago
There should be some easy method to solve this, Can any one have?
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.
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