Thursday 23 July 2015

Concept of Series-03

Find the wrong number.
1.        24      14       26      17      28       16         30     [Ans:-(2)]
(1) 14    (2) 17   (3) 36   (4) 16   (5) 28
2.        5         6       16       57       248     1245     7506       [Ans:-(4)]
(1) 6     (2) 16    (3) 57   (4) 248   (5) 124
3.        2         9        32       105      436     2195      13182     [Ans:-(5)]
(1) 2195   (2) 105 (3) 436 (4) 9   (5) 32
4.       11        6         8         12        26       67.5       205.5     [Ans:-(1)]
(1) 8   (2) 6     (3) 26   (4) 67.5   (5) 12
5.        3        16       113      673      3361     13441     40321    [Ans:-(3)]
(1) 13441 (2) 673   (3) 16   (4) 3361   (5) 28

Solution:
Detailed Explanation:
Concept: More than 90% questions can be classified on the basis of “slop”. Maximum Slop, Average Slop and Minimum Slop – these are the mainly three types or slop. There is one more type of slop - mean slop.
(1) In the Minimum Slop, the terms are obtained by adding some numbers. In this type of slop, terms are not become multiple.

(2) In other two types of slops, terms become multiple. In the Average Slop, terms become multiple equally, i. e., slops are as: ×2×2×2×2×2…. Or ×1.5×1.5×1.5×1.5×1.5…. or ×3×3×3×3×3×3×……., and something added or subtracted also.
 
(3) In the Maximum Slop, terms become multiple, but not equally. It is either increasing or decreasing  i. e., slops are as: ×1×2×3×4×5…. Or ×1.5×3×4.5×6×7.5…. or ×2×4×6×8×10×……., and something added or subtracted also.

(4) In the Mean Slop, terms become multiple, but not equally, but not so much sharp. It is either increasing or decreasing i. e., slops are as: ×0.5×1×1.5×2.5×3…. etc. and some thing added or subtracted also.

(5) There is an “Ups and down” series also. In this series there are two types; one, in which multiplication and division are in alternately used, and another, in which addition and subtraction are alternately used. If slop is sharp, then the case is of probably of multiplication and division and if the slop is less sharp, then the case is of probably of addition and subtraction.

(6) Some other rule may be associated in the series. Sometimes, any term in a series is the sum of its just previous two terms throughout the series. Or, any term in a series is the product of its just previous two terms throughout the series.     

1. Solution: This is an “Ups and down” series (type v). Here continuously divided by 2, then multiply by and so on. Also, when divided by 2, then 2 is added and when multiplied by 2, then 2 is subtracted and so on.

               ÷2+2     ×2-2      ÷2+2     ×2-2      ÷2+2     ×2-2      ÷2+2 
1. Solution: 24          14          26         17          28         16         30            
Here 17 is wrong.

2. Solution: This is type III series. Slop is “Maximum”. Terms are multiplied by 1, 2, 3, 4, 5, 6 respectively and 12, 22, 32, 42, 52, 62 are successively added.

             ×1+12    ×2+22     ×3+32     ×4+42     ×5+52       ×6+62 
2. Sol.: 5            6            16          57         248         1245          7506     
248 is wrong.

3. Solution: This is also a type III series. Slop is “Maximum”. Terms are multiplied by 1, 2, 3, 4, 5, 6 respectively; but the added terms, which are multiplied, are complimentary to eight. 1+7 = 8, 2+6 = 8, 3+5 = 8, 4+4 = 8, 5+3 =8 and so on.

             ×1+1×7   ×2+2×6    ×3+3×5     ×4+4×4     ×5+5×3       ×6+6×2      
3. Sol.: 2              9              32            105            436           2195           13182 
32 is wrong.

4. Solution: This series is an example of “Mean Slop” (Type IV). Terms are multiplied by 0.5, 1, 1.5, 2, 2.5 3 respectively; and then added 0.5, 1, 1.5, 2, 2.5 3 respectively also.

             ×(0.5)+(0.5)  ×(1)+(1)  ×(1.5)+(1.5)  ×(2)+(2)  ×(2.5)+(2.5)  ×(3)+(3)  
4. Sol.: 11                  6              8                   12             26                 67.5        205.5  

8 is wrong.


5. Solution: This is also a type III series. Slop is “Maximum”. Terms are multiplied by 8, 7, 6, 5, 4, 3 respectively; but 7, 6, 5, 4, 3, 2 are subtracted and added alternately throughout the series.

             ×8-7   ×7+6     ×6-5      ×5+4       ×4-3          ×3+2

5. Sol.: 3        16        113        673        3361        13441        40321 

16 is wrong.
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