David_M
Hot Rolled
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- Sep 30, 2014
- Location
- Midway, GA, USA
Give the answer in number of turns.
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OT- Math question about a ratio from an old SAT exam
- Thread starter David_M
- Start date
- Replies 132
- Views 9,150
BoxcarPete
Stainless
- Joined
- Nov 30, 2018
- Location
- Michigan, USA
Is this some kind of trick question? If there were a "4" as a choice I'd consider it because it goes around the circle for another "turn" but it's just 3 otherwise.
Booze Daily
Titanium
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- Sep 18, 2015
- Location
- Ohio
Well circumference is pi x dia, so if one dia is 3x larger the circumference will be 3x larger. So 3.
Mark Rand
Diamond
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- Jul 9, 2007
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- UK Rugby Warwickshire
NOTA. As Pete says, it'll go round four times.
This is one of the features of epicyclic gears.
This is one of the features of epicyclic gears.
David_M
Hot Rolled
- Joined
- Sep 30, 2014
- Location
- Midway, GA, USA
BoxcarPete and Mark got it!
It wasn't intended to be a trick question. They just got it wrong. It's worth watching.
It wasn't intended to be a trick question. They just got it wrong. It's worth watching.
CarlBoyd
Hot Rolled
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- Jul 16, 2007
- Location
- Orlando, Florida
plastikdreams
Diamond
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- May 31, 2011
- Location
- upstate nj
It's nine...if you divide 3 by 1 you get three, then multiply 3 by the answer and you get 9...nine divided by .33 (1/3) is 27.27...the square root of 27.27 is 5.222 multiply that by pi and get 16.405...tan(16.405) is .29, round up to .3 and multiply by 30 and bam 9.
plastikdreams
Diamond
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- May 31, 2011
- Location
- upstate nj
Thats interesting. In a sense its a matter of where circle A is viewed from. Ie looking out from the centre of circle B or directly down over circle A.
Either way I blame Boozy D
You have to look at the circles not as circles but as lines bent into a circle...but not any circle, a perfect circle with no chords or defects. It's an object of such perfection that no other 2 circles are as perfect...nor will there ever be.
And the Lord said "let there be lulz," and there was lulz.
beege
Stainless
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- May 18, 2007
- Location
- Massachusetts
So here's the logic I find in this If I were to roll the smaller circle on a line three times the length of the circumference of the smaller circle, the center of the circle travels the same length as the line. Three rotations. Now if I make the line into a circle, the center of the circle will travel 1 + 1/3 the circumference of the large circle, or 4/3. It's all about how far the center travels. 4 rotations.
EPAIII
Diamond
- Joined
- Nov 23, 2003
- Location
- Beaumont, TX, USA
"OK, Lucy; you have some splaining to do."
This is not the first or only time the people who wrote those exams got it wrong. I can recall a number of times where I had to stop and think, now what were they thinking, in order to bet the desired answer and a better grade.
This is not the first or only time the people who wrote those exams got it wrong. I can recall a number of times where I had to stop and think, now what were they thinking, in order to bet the desired answer and a better grade.
Conrad Hoffman
Diamond
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- May 10, 2009
- Location
- Canandaigua, NY, USA
Dang! That's actually quite interesting.
jim rozen
Diamond
- Joined
- Feb 26, 2004
- Location
- peekskill, NY
Roll the big circle out flat, it's a rack and the small one a pinion. Length of rack is 3 times the circumference of the pinion.
Conrad Hoffman
Diamond
- Joined
- May 10, 2009
- Location
- Canandaigua, NY, USA
You didn't watch the video. No pi for you.
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