Total savings = 200 + 200 + 200 + 240 + 280 + ... to n months = 11040

= 120 + 80 + 160 + 40 + 200 + 240 + ....n terms
= 40 + 80 + 120 + 160 + 200 + 240 + ...n terms
= n/2[2a + (n-1)d] + 80 + 40 = 11040
= n/2[240 + (n-1)40] = 10920
= n[6+n-1] = 546
= n[n+5] = 546
n = 21

Except Horse, remaining all belong to female category.

Hind - Female Deer

Ewe - Female Sheep

Bitch - Female Dog. 

Here the given series follows a pattern that, multiplying the number with odd numbers in decreasing order starting with 13. That is,

6 × 13 = 78

65 × 11 = 858

858 × 9 = 7722

7722 × 7 = 54054

54054 × 5 = 270270

Hence, the wrong number is 54055

Given 311   230   294   ?   281   256

311 - (9x9) = 230

230 + (8x8) = 294

294 - (7x7) = 245

245 + (6x6) = 281

281 - (5x5) = 256

Hence, the missing number in the given series is 245.

Here the given series follows a pattern that,

2² - 0 = 4  

3² - 1 = 8  

4² - 2 = 14

5² - 3 = 22

6² - 4 = 32

Hence, the missing number is 32

Method 2 ::

The difference between 4 and 8 is 4, the difference between 8 and 14 is 6, the difference between 14 and 22 is 8. So the next difference between 22 and the next number will be 10 since it follows (4,6,8,10 - add +2 each time)

Hence, 22 + 10 = 32 is the missing number.

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  S n = n ( a 1 + a n ) 2 Where n = number of terms, a1 = first term, an = last term

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

Now given Arithmetic Series is 

2, 5, 8, 11,...

Here a1 = 2,  d = 3, n = 36 

Now,  $$\begin{gathered} a n = a 1 + n - 1 d \\ a 36 = 2 + 36 - 1 3 = 105 + 2 = 107 \end{gathered}$$

Now, Sum to 36 terms is given by

S 36 = 36 ( 2 + 107 ) 2 = 36 x 109 2 = 3924 2 = 1962

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

Here the given series 7  18  42  94  204 follows a pattern that, 

7

7 ×2+4 = 18

18 ×2+6 = 42

42 ×2+10 = 94

94 ×2+16 = 204

Similarly,

4

4 ×2+4 = 12

12 ×2+6 = 30

30 ×2+10 = 70

70 ×2+16 = 156

Hence, the value of P = 156.

The next number in the series is

143 143 136 110

      0    7      26 (Differences)

  $$\begin{gathered} 1 3 - 1 , 2 3 - 1 , 3 3 - 1 , 4 3 - 1 , . . . \\ Now the next number is given by \\ 110 - ( 4 3 - 1 ) = 110 - 63 = 47 . \end{gathered}$$

Pattern is

• 3

• 3 x 3.5 = 10.5

• 10.5 x 3.5 = 36.75

• 36.75 x 3.5 = 128.625

• 128.625 x 3.5 = 450.187

The given number series is 90 72 56 42 36 20

9 x 10 = 90

8 x 9 = 72

7 x 8 = 56

6 x 7 = 42

5 x 6 = 30 (not 36) 

4 x 5 = 20

Hence, the odd man in the given number series is 36.