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Satyam Rai

· started a discussion

· 1 Months ago

Please explain it properly, I can't understand the concept of how you've provided the solution.

Question:

DIRECTIONS: What will come in the place of question mark (?)?


15  21  39  77  143  (?)

Options:
A) 243
B) 240
C) 253
D) 245
E) None of these
Solution:

The pattern  is:

15 + 6 = 21

21 + 18 (= 6 + 12) = 39

                

39 + 38 (= 18 + 20) = 77

                

77 + 66 (= 38 + 28) = 143

                
143 + 102 (=66 + 36) = 245

Knowledge Expert

· commented

· 1 Months ago

15-21-39-77-143-
take difference of these numbers you get
21-15 =6 and so on
6-18-38-66-
taking difference of these
12-20-28
and there difference is constant , that is
8-8
so adding one more 8 here and going backwards to complete the tree
12-20-28-36
6-18-38-66-102
15-21-39-77-143-245
hence 245 is the answer

Talented Boy

· commented

· 1 Months ago

FIND DIFFERENCE BETWEEN NUMBERS,THESE DIFFERENCE ITSELF DIFFER BY SAME NUMBER.

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