Series Completion
Series
completion section deals with questions in which series of numbers or
alphabetical letters are given, which are generally called as terms of the
series. These terms follow a certain pattern throughout.
The
candidate is required to recognize this pattern and either complete the given
series with the most suitable alternative or find wrong in the series.
1. In following question, a number
series is given with one term missing. Choose the correct alternative that will
same pattern and fill in the blank spaces.
2, 3, 5, 7, 11, x, 17
A.
12 B. 13 C. 14 D. 15
Answer: B . 13
Clearly,
the given series consists of prime numbers starting from 2. The prime number
after 11 is 13.
So,
13 is the missing number.
2. 20, 19, 17, x , 10, 5
A.
12 B. 13 C. 14 D. 15
Answer: C . 14
The Pattern is
- 1, - 2,...
.'.
Missing number = 17 - 3 = 14.
Three
types series 1.Number series
2. Alphabet series
3. letter series
3.
Which of the following is wrong in the following series?
2, 7, 25, 77, 238, 723
A – 7 B – 238 C – 77 D - 25
Answer − Option D
Explanation − The given series is −
31– 1, 32 – 2, 33
– 3, 34 – 4, ….
The number in place of 25 should be 24 = 33
– 3.
4.
2, 3, 5, 7, 11, x, 17
A. 12 B. 13 C. 14 D. 15
Answer: B . 13
Clearly, the given series consists of prime
numbers starting from 2. The prime number after 11 is 13.
So, 13 is the missing number.
5.
19, 2, 38, 3, 114, 4,
A. 228 B. 256 C. 352 D. 456
Answer: D . 456
The sequence is a combination of two series
:
I.
19, 38, 114, (....)
and II. 2, 3, 4
The pattern followed in I is * 2, * 3,...
.'. Missing number = 114 * 4 = 456.
6. 1,
10, 9, 16, 25, 26, 49
1. 1 2. 16 3. 26 4. 9 5. 49
Answer & Explanation
Sol: Option 2
Explanation: The given sequence is a
combination of two series:
I. 1, 9, 25, 49 and II. 10, 16, 26
The pattern in I is +8, +16, +24.
The sequence in II is 32 + 1, 42 + 1, 52 +
1
So, 16 is wrong and must be replaced by (42
+ 1) i.e. 17.
7.
3, 6, 18, 72,
A. 144 B. 216 C. 288 D. 360
Answer: D . 360
The pattern is * 2, * 3, * 4,...
.'. Missing number = 72 * 5 = 360.
8.
66, 36, 18,
A. 3 B. 6 C. 8 D. 9
Answer: C . 8
Each number is the series is the product of
the digit of the preceding number.
Thus, 6 * 6 = 36,
3 * 6 = 18
and so on.
.'. Missing number = 1 * 8 = 8.
9.
A , C , F , , O
A.
H B.I
C.J D . K
Ans:
C.J
.
A , C , F , , O follows 1 , 3, 6 , 10 , 15
1+2 , 3+4 , 6+4 , 10+5……..
10.
Z , Y , W , T , ….
A.
P B.R C. S D. Q
Ans
: A.P
Z-
1 , Y-2,W-3 , T-4 ……. = 25- 1 , 25-2,23-3
, 20- 4 ……
Y
, W ,T,P -----
P
is next alphabet
11.
A, C, F, H, ?, M
A.
L B. K C. J D. I
Answer: B . K
The
letters are alterntely moved two and
three steps forward to obtainthe successive terms.
12.
BF, CH, ?, HO, LT
A.
DN B. EL C. EK D. EM E. FJ
Answer: C . EK
The
first letter of the first, second, third, .... terms are respectively moved
one, two, three,... steps forward
while
the second letter are respectively moved two, three, four,... steps forward
to obtain the corresponding letters of
the successive terms.
13.
BEH, KNQ, TWZ, ?
A.
IJL B. CFI C. BDF D. ADG
Answer: B . CFI
All
the letters of each term are moved nine steps forward to obtain the
corresponding letters of the next term.
14. In alphabet series, some alphabets
are missing which are given in that order as one of the alternatives below it.
Choose the correct alternative.
_ _ aba _ _ ba _ ab
A. abbba B. abbab C. baabb D. bbaba
Answer: B . abbab
The series is ab / ab / ab / ab / ab /
ab.
Thus, the pattern ab is repeated.
15. _ _ babbba _ a _ _
A. ababb B. baaab C. bbaba D. babbb
Answer: D . babbb
The series is bababb / bababb.
Thus, the pattern bababb is repeated.
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