The Math Forum

Ask Dr. Math - Questions and Answers from our Archives
Associated Topics || Dr. Math Home || Search Dr. Math

Duration of a Clock's Strike

Date: 01/21/2004 at 19:50:30
From: Stacey
Subject: how long does it take for a clock to strike 10

If it takes seven seconds for a clock to strike 7 o'clock, then how 
long does it take to strike 10 o'clock?  It seems as if the answer is
10, but I have worked a problem just like this before and I can't
remember how to start it.

Date: 01/22/2004 at 09:04:23
From: Doctor Peterson
Subject: Re: how long does it take for a clock to strike 10

Hi, Stacey.

The answer depends on how you think of a strike.  If each "bong" lasts 
until the next one starts, and you are counting how long the sounds 
last, then you are right:

strikes     1     2     3     4     5     6     7
seconds  0     1     2     3     4     5     6     7

Each strike takes a whole second, and ten of them will take 10 

But if you think only of the actual strikes (when the bell is hit), 
and ignore how long the sound lasts afterward, then the picture is 

strikes  1      2      3      4      5      6      7
         *      *      *      *      *      *      *
seconds  0     1     2     3     4     5     6     7

Now there are 6 spaces BETWEEN strikes, which each last MORE than a 

Can you finish the problem, interpreting it that way?

Of course, in reality each bong would take some time that may be more 
or less than the time between strikes, and we don't have enough 
information to determine the total time we hear the clock.

- Doctor Peterson, The Math Forum 
Associated Topics:
Elementary Puzzles
Middle School Puzzles

Search the Dr. Math Library:

Find items containing (put spaces between keywords):
Click only once for faster results:

[ Choose "whole words" when searching for a word like age.]

all keywords, in any order at least one, that exact phrase
parts of words whole words

Submit your own question to Dr. Math

[Privacy Policy] [Terms of Use]

Math Forum Home || Math Library || Quick Reference || Math Forum Search

Ask Dr. MathTM
© 1994- The Math Forum at NCTM. All rights reserved.