OT- Math question about a ratio from an old SAT exam

Thread: OT- Math question about a ratio from an old SAT exam

1. Hot Rolled
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OT- Math question about a ratio from an old SAT exam

Give the answer in number of turns.

2. Hot Rolled
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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.

3. Stainless
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Well circumference is pi x dia, so if one dia is 3x larger the circumference will be 3x larger. So 3.

4. Diamond
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NOTA. As Pete says, it'll go round four times.

This is one of the features of epicyclic gears.

5. I would say 3

6. Its ok Bob, your secrets safe with me

7. Aluminum
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I got 3.

8. Hot Rolled
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BoxcarPete and Mark got it!

It wasn't intended to be a trick question. They just got it wrong. It's worth watching.

9. Hot Rolled
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Originally Posted by Booze Daily
Well circumference is pi x dia, so if one dia is 3x larger the circumference will be 3x larger. So 3.
Bingo, correct answer and correct logic.

CarlBoyd

10. 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.

11. 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

12. Originally Posted by Demon73
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.

13. Originally Posted by plastikdreams
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.

14. 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.

15. Diamond
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"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.

Originally Posted by plastikdreams
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.

16. I lurnt sumthin today

17. Dang! That's actually quite interesting.

18. Diamond
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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.

19. You didn't watch the video. No pi for you.