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Divide by 2 indefinitely, get result (Posted on 2024-06-11) Difficulty: 3 of 5
A student John starts with the familiar series 1 + 1/2 + 1/4 + 1/8 + . . . .

He then takes the average of each adjacent pair of terms and inserts it between the terms to obtain the new series 1 + 3/4 + 1/2 + 3/8 + 1/4 + . . . .

He divides this by two, because there are now twice as many terms as before. That gives

1/2 + 3/8 + 1/4 + 3/16 + 1/8 + ...

He repeats the process indefinitely. For example, the next pair of steps gives

1/2 + 7/16 + 3/8 + 5/16 + 1/4 + 7/32 + 3/16 + 5/32 + 1/8 + ...

then

1/4 + 7/32 + 3/16 + 5/32 + 1/8 + 7/64 + 3/32 + 5/64 + 1/16 + ...

What exact limit will the series approach?

  Submitted by K Sengupta    
Rating: 5.0000 (1 votes)
Solution: (Hide)
The required exact limit is 3/2.

For an explanation, refer to the solution submitted by Brian Smith in this location.

Comments: ( You must be logged in to post comments.)
  Subject Author Date
Some ThoughtsComputer solutionLarry2024-06-12 08:02:25
Puzzle ThoughtsK Sengupta2024-06-12 07:53:16
SolutionAnalytic SolutionBrian Smith2024-06-11 23:40:16
SolutionsolutionCharlie2024-06-11 21:47:00
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