perplexus.info :: General : A clock tower

A clock tower (Posted on 2002-04-24)

A clock tower bell sounds to mark off every hour with the number of bells equal to the hour (three consecutive bells sound at three o'clock, etc). The last bell marks the exact beginning of the hour.

The sounding of the bells for six o'clocks starts at 30 seconds before six.

Assuming that the bells are always evenly and equally spaced in time, how long before noon must the sounding of the bells begin?

Submitted by levik

Rating: 2.4000 (10 votes)

Solution: (Hide)

While the six o'clock bells take 30 seconds, it is incorrect to assume that each bell takes 5 seconds. If you think about how the bells are sounded, you will realize that they are instaneous, and it is the periods between the bells that make up for the time delay.
For six bells, there are five pauses, adding up to 30 seconds, which means that each pause takes 6 seconds.
For the bells to strike twelve times, there will be 11 such pauses, taking 66 seconds. That means that to mark noon, the clock tower starts ringing its bells one minute and six seconds before.

Comments: ( You must be logged in to post comments.)

Subject	Author	Date
answer	K Sengupta	2007-04-01 15:06:18
I was wrong :(	Brittany	2004-04-12 16:02:03
Solution	sassy	2004-04-12 13:34:30
solution	Jesse	2003-09-21 05:52:08
Response	Lawrence	2003-08-31 23:59:47
re: Math	Dacre	2003-08-28 12:38:07
re: i think	Sarah	2003-03-23 12:05:00
i think	Sarah	2003-03-23 12:04:20
ummm	Cassandra Wallace	2003-02-12 17:27:34
Answer	Hershel	2003-01-14 12:47:03
Math	Angela	2002-12-06 08:40:10
my guess	maverick	2002-11-30 00:26:28
Solution	Jim Lyon	2002-07-25 11:41:01

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