Clock Times and Fibonacci Differences

XAT 2018 · Quantitative Ability & Data Interpretation · Hard · Quantitative Aptitude

An antique store has a collection of eight clocks. At a particular moment, the displayed times on seven of the eight clocks were as follows: 1:55 pm, 2:03 pm, 2:11 pm, 2:24 pm, 2:45 pm, 3:19 pm and 4:14 pm. If the displayed times of all eight clocks form a mathematical series, then what was the displayed time on the remaining clock?

  1. A.

    1:53 pm

  2. B.

    1:58 pm

  3. C.

    2:18 pm

  4. D.

    3:08 pm

  5. E.

    5:08 pm

Answer

B

Explanation

Time gaps between consecutive given times: 8m, 8m, 13m, 21m, 34m, 55m. Notice 8, 13, 21, 34, 55 are Fibonacci numbers. The standard Fibonacci sequence is 1, 1, 2, 3, 5, 8, 13... The initial 8 min gap between 1:55 and 2:03 can be split into 3 min and 5 min gaps. Inserting 1:58 pm gives gaps: 3m (1:55 to 1:58), 5m (1:58 to 2:03), 8m, 13m, 21m, 34m, 55m.

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