# Reading, understanding and following instructions

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#### Thread man

##### Well-Known Member
If you’re easily offended probably best not to read any more.

I posted a thread with the title Mathematical Question. In the first post I wrote:

“I've always regarded myself as being good at geometry (and trigonometry) and I suppose you have to be working with threads. However, and to my surprise, I got the wrong answer to this and I even regarded it as simple!

Use your head or pencil and paper but don't cut anything out. That'd be cheating ☺

How many revolutions of the small circle (R1) will it take to circle the circumference of the large circle (R3) to arrive back at the starting point?

Any answers?”

That was, or so I thought, a simple instruction. Already in the second post was an incorrect answer and the same as I’d arrived at when I saw the video on Youtube. Then things got “interesting”.

I don’t know what to say to post 3. The 5th post gave the Youtube video where I saw the question. To me posting that spoiled everything as I could just as well have posted that video myself from the beginning.

All of this reminds me of when I was at school and the teacher said he had a test for us. We were all given 3 sheets of paper with what appeared to be relatively simple questions and a line under each question where the answer could be written.

The first sentence was “Read the paper carefully before answering any questions”. Anyone doing that would have arrived at the last sentence that stated “Don’t answer any questions and simply initial the paper on the top right hand side of the first page and return to me.”

In a class of 25 how many returned the paper with only their initials on it? Not one!

Getting back to the original thread it still fascinates me that the answer is always the Pi D equation + 1. Two identical diameter circles 1 + 1 and the answer is 2, 3 to 1 and the answer is 4 and the stationary circle, even if 15 times the diameter of the small circle is 15 + 1.

A coin of diameter 2R is held stationary while a smaller coin of diameter 2r is rolled around its circumference until it returns to its starting position. How many revolutions does the smaller coin make ?

The number of revolutions (N) can be found by dividing the distance the center of the coin has traveled (T) by its circumference...

N = T/(2*pi*r)

The center of the smaller coin travels around a circle with a radius of (R+r); thus T = 2*pi*(R+r) and...

N = (R+r)/r = R/r +1

In the case of R = r (two identical coins), N = 2.

mklotz

Where did you fnd those formula?

Could you put numbers in each formula? If it makes things easy just take both coins as having a diameter of 2 whatevers.

Uhmm ... are you in a position to give instructions to this group? Last time I checked, this was a forum, not a classroom.

Uhmm ... are you in a position to give instructions to this group? Last time I checked, this was a forum, not a classroom.
If you read my first post again then let me know where I'm giving instructions to anyone.

If you read my first post again then let me know where I'm giving instructions to anyone.

The title of this thread is "Reading, understanding, and following instructions."

From the initial post in this thread:
That was, or so I thought, a simple instruction.

Perhaps I have misunderstood - always a possibility! - but the implication seemed to be that you were talking about people not following your instructions. My apologies if I have misunderstood!

Note also the title of this thread: "Reading, understanding, and following instructions."

Perhaps I have misunderstood - always a possibility! - but the implication seemed to be that you were talking about people not following your instructions in the other thread. My apologies if I have misunderstood!
I thought the (true) example I gave explained the thread title.

All of this reminds me of when I was at school and the teacher said he had a test for us. We were all given 3 sheets of paper with what appeared to be relatively simple questions and a line under each question where the answer could be written.

The first sentence was “Read the paper carefully before answering any questions”. Anyone doing that would have arrived at the last sentence that stated “Don’t answer any questions and simply initial the paper on the top right hand side of the first page and return to me.”

In a class of 25 how many returned the paper with only their initials on it? Not one!

I was in that class and didn't follow the instructions either Let's just say it was a mistake I never tried to repeat although I probably have.

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