Question Details

Determine the number that should replace the question mark (?) in the following sequence.

131, 143, 157, 175, 201, ?

Options

A

221

B

287

C

243

D

299

E

265

Show Answer

Correct Answer :

Option C

243

Solution :

The correct option is 243.


To find the missing number in the sequence, let's analyze the difference between consecutive terms:


First term: 131

Second term: 143

143-131=12


Third term: 157

157-143=14


Fourth term: 175

175-157=18


Fifth term: 201

201-175=26


Now, let's observe the sequence of first differences:

12, 14, 18, 26


Next, let's calculate the second differences (the differences between consecutive first differences):

14-12=2

18-14=4

26-18=8


The second differences are doubling at each step (2, 4, 8, ...), following powers of 2:

21=2

22=4

23=8


Following this pattern, the next second difference should be:

24=16


Adding 16 to the previous first difference (26) gives the next difference to add to 201:

26+16=42


Finally, add 42 to the last term (201) to find the missing number (?):

201+42=243


Thus, the number that replaces the question mark is 243.

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