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If Big Ben chimes four o'clock in 6 seconds, how long does it take to inform me it is ten o'clock?

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When a clock chimes, what actually takes the time? Why can four o'clock not be rung instantly?

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Why is the word "inform" used in the question?


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20 seconds.

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The length of time taken to ring any specific time consists of the length of the gaps between the chimes. One o'clock is chimed instantly. Two o'clock takes the length of the pause between the start of the two chimes. Three o'clock two pauses, and four o'clock three pauses:

1st chime - pause - 2nd chime - pause - 3rd chime - pause - 4th chime


We are told Big Ben takes 6 seconds to chime four o'clock which means each pause is 2 seconds long. To chime ten o'clock, 9 pauses are needed. 9 pauses at 2 seconds for each pause requires 18 seconds.

However, to be certain that ten o'clock has been chimed and not eleven o'clock we need to wait an extra 2 seconds (one more pause) to check that the chiming has indeed finished after ten chimes and that an eleventh chime is not going to be chimed.

10 chimes (9 pauses) plus one extra pause = 20s


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