1. ## Dizzy Clock

I don't even know where to start this one. It comes from the GMAT review test book.

A certain clock marks every hour by striking a number of times equal to the hour and the time required for a stroke is exactly equal to the time interval between strokes. WHAT???
At 6:00 the time lapse between the beginning of the first stroke and the end of the last stroke is 22 seconds. At 12:00, how many seconds elapse between the beginning of the first stroke and the end of the last stroke?
WHAT???

The wording is horrific, to say the least. What would you do if you face a problem like this on the GMAT or GRE or SAT or whatever? What's the equation set up?

2. ## Re: Dizzy Clock

Originally Posted by harpazo
I don't even know where to start this one. It comes from the GMAT review test book.

A certain clock marks every hour by striking a number of times equal to the hour and the time required for a stroke is exactly equal to the time interval between strokes. WHAT???
At 6:00 the time lapse between the beginning of the first stroke and the end of the last stroke is 22 seconds. At 12:00, how many seconds elapse between the beginning of the first stroke and the end of the last stroke?
WHAT???

The wording is horrific, to say the least. What would you do if you face a problem like this on the GMAT or GRE or SAT or whatever? What's the equation set up?
6.00 would sound like this:

DONG QUIET DONG QUIET DONG QUIET DONG QUIET DONG QUIET DONG

The time for a DONG is the same for a QUIET. There are 11 times all together for 6:00 (6 dongs and 5 quiets in between).

From the beginning to the end takes 22 seconds. So the time for a DONG is 2 seconds (and also the time for a QUIET is 2 seconds).

Now think about 12:00 in the same way. You don't need to set up an equation.

3. ## Re: Dizzy Clock

Clock repair shop ad: If your clock don't tick, tock to us!

4. ## Re: Dizzy Clock

Originally Posted by Debsta
6.00 would sound like this:

DONG QUIET DONG QUIET DONG QUIET DONG QUIET DONG QUIET DONG

The time for a DONG is the same for a QUIET. There are 11 times all together for 6:00 (6 dongs and 5 quiets in between).

From the beginning to the end takes 22 seconds. So the time for a DONG is 2 seconds (and also the time for a QUIET is 2 seconds).

Now think about 12:00 in the same way. You don't need to set up an equation.
Here is what I found online:

A clock is going to chime 6 times at 6:00. The first chime starts exactly at 6:00, and the last one is 22 seconds after, or 6:00:22. The amount of time between chimes is always the same.

How much time will it take for the clock to chime 12 times at 12:00?

My guess is 22 seconds to chime 6 times. The first chime is at the 6:00 mark, so five more chimes in the next 22 seconds. The time between each chime is 22/5. That's 4.4 seconds between each chime.

At 12:00, the clock will start to chime 12 times. So, 1 chime at 12:00 exactly, and 11 more chimes each at 4.4 seconds apart. That's 48.4 seconds in total.

5. ## Re: Dizzy Clock

You are not accounting for the fact that the actual chime takes up time too. And the chime takes the same length of time as the silences between them.

6. ## Re: Dizzy Clock

Originally Posted by Debsta
You are not accounting for the fact that the actual chime takes up time too. And the chime takes the same length of time as the silences between them.

Each stroke takes a certain amount of time, and that same amount of time is taken between strokes. This results in a chime of Bong ... Bong ... Bong ... (etc) instead of BongBongBong....

When chiming x times, there will be (x - 1) pauses between strokes, so it will take (2x - 1) intervals to complete the chime.
At 6:00, it will take 2(6) - 1, or 11 intervals and we are told this lasts 22 seconds. Therefore, each interval lasts 2 seconds.
At 12:00, the chiming will take 2(12) - 1, or 23 intervals which will last 46 seconds.

Answer: 46 seconds. If this is wrong, I give up!

7. ## Re: Dizzy Clock

Correct! Now read the original question again. Makes sense now doesn't it!

8. ## Re: Dizzy Clock

Very good. Moving on.