GATE Questions

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The given number series is 720, 732, 708, 742, 696

720

720 + 12 = 732

732 - 24 = 708

708 + 36 = 744 (Not 742)

744 - 48 = 696

Hence, the odd man in the given number series is 742.

Arithmetic Series ::

An Arithmetic Series is a series of numbers in which each term increases by a constant amount.

How to find the sum of the Arithmetic Sequence or Series for the given Series ::

When the series contains a large amount of numbers, its impractical to add manually. You can quickly find the sum of any arithmetic sequence by multiplying the average of the first and last term by the number of terms in the sequence.

That is given by Sn = n(a1 + an)2 Where n = number of terms, a1 = first term, an = last term

Here Last term is given by an = a1 + n-1d where d = common difference

Now given Arithmetic Series is 

2, 5, 8, 11,...

Here a1 = 2,  d = 3, n = 36 

Now, $$\begin{gathered} an= a1 + n - 1d \\ a36= 2 + 36 - 13 = 105 + 2 = 107 \end{gathered}$$

Now, Sum to 36 terms is given by

S36 = 36(2 + 107)2 = 36 x 1092 = 39242 = 1962

Therefore, Sum to 36 terms of the series 2, 5, 8, 11,... is 1962.

Here given series follows a pattern that

0.25, 8, 128, 1024, ?

0.25 x 32 = 8

8 x 16 = 128

128 x 8 = 1024

1024 x 4 = 4096

The given number series is 180, 90, 60, 40, 36

It follows a pattern that,

180 x 1/2 = 90

90 x 2/3  = 60

60 x 3/4  = 45 (NOT 40)

45 x 4/5  = 36

Hence, the wrong number in the given series is 40.

Given number series is 514   470   ?   415   404

Here the pattern it follows is

514

514 - 44 = 470

470 - 33 = 437

437 - 22 = 415

415 - 11 = 404

Hence, the missing number in the given number series is 437.

$$\begin{gathered} 13 x ? + 47 x 114 x 539 = 31100 x 2000 \\ ? = 378 x 3 \\ ? = 1134 \end{gathered}$$

The given number sequence is 101, 98, 93, 86, 75, ?

101

101 - 3 = 98

98 - 5 = 93

93 - 7 = 86

86 - 11 = 75

75 - 13 = 62

Here the series follows a pattern that consecutive subtraction of prime numbers.

Hence, the next number in the sequence is 62.

The given number series 410, 409, 413, 404, ? , follows a pattern that 

410

$$\begin{gathered} 410 - 13 = 409 \\ 409 + 22 = 413 \\ 413 - 33 = 404 \\ 404 + 42 = 420 \end{gathered}$$

Hence, the next number in the given series is 420.