How to solve series completion problems?

A series is continuous collection of numbers, letters in a specific sequence. In series completion questions, a series will be given and the candidate is expected to complete the series by choosing the correct one from the given alternatives. In verbal reasoning, three types of series completion questions are found,

1.       Number Series

In number series, some numbers will be given and we need to find out the missing one. By analyzing the given series we can find some pattern by which the series is appearing. Thus we can find exact number which will complete the series.

Type 1: Completing the given series by finding the missing term.

Example: 1, 2, 4, 7, 11, ?

        a). 15     b).16      c). 17     d). 12

Solution: b). 16

By looking in to the series we can see,

Example: 48, 24, 72, 36, 108, ?

        a). 112   b). 224  c). 244   d). 54

Solution: d). 54

Look at the series,

Practice Questions:-

1. 1, 4, 9, 16, ?

a). 19             b). 25     c). 20     d). 36

2. 1, 27, 125, 343, ?

a). 729           b). 445  c). 556   d). 900

3. 2, 6, 12, 20, 30, ?

a). 50             b). 40     c). 42     d). 36

4. 7, 26, 63, 124, ?

a). 222           b). 156  c). 215   d). 216

5. 1, 4, 12, 32, ?

a). 80             b). 96     c). 64     d). 70

Answers

1. b                 2. a         3. c         4. c         5. A

Type2: Finding the wrong term in the given series

Example: 121, 144, 158, 169, 196

        a). 158   b). 121  c).169    d). 196

Solution: a).158

A close look in to the series will give the idea that this is a continuous series of perfect squares of 11, 12, 13, 14. So 158 is the wrong term in this series.

PRACTICE QUESTIONS

1. 140, 165, 175, 215, 240

        a). 140   b). 165  c). 175 d). 240

2. 15, 17, 21, 28, 45

        a). 28     b). 21     c). 17 d). 15

3. 2, 5, 10, 50, 500, 5000

        a). 2       b). 50     c). 500 d). 5000

4. 0, 1, 1, 2, 3, 4, 8

        a). 2       b). 0       c). 4 d). 3

5. 2, 3, 4, 4, 6, 8, 9, 12, 16

        a). 4       b). 9       c). 12 d). 16

Answers

1.c                  2.a                          3.d                          4.c                          5.b

2.    Letter series

Here a series of alphabetic letters or group of letters will be given. Candidates are expected to identify the rule by which the series is continuing and pick the wrong one out or find the missing term.

Example: Which term comes next in the series?

AD, GJ, MP, SV, ?

a). WZ           b). YB       c). SP         d). YZ

Solution: YB

Practice Questions:-

1. A, C, F, J, ?, ?

a). K, L           b). O, U                          c). M, O           d). N P

2. GH, JL, NQ, SW, YD, ?

a). EL             b). FJ        c). EJ        d). FL

3. AZY, BUT, CXW, DWV, ?

a). VUE         b). VEU           c). EVA             d). EVU

4. AB, DEF, HIJK, MNOPQ, ?

a). RSTUVW                b). STUVWX         c). TUVWXY           d). UVWXYZ

5. DHL, PTX, BFJ, ?

a). NRU        b). RUZ          c). KOS              d). CGK

Answers

1. b                 2. d                         3. d                         4. b                         5. A