Mateo and Yvonne are using old records for their mousetrap racers.

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Luckygal

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Mateo and Yvonne are using old records for their mousetrap racers. Mateo is using LPs, which have a diameter of 30cm. His racer's wheels turn 5 times. Yvonne is using 45s, which have a diameter of 17.5cm. Her racer's wheels turn 8.5 times. Who's racer's wheels travels the farthest?

I don't know how to start the equation. Do I divide 5 by 30 and 8.5 by 17.5? Or do I multiply 5 by 30 and 8.5 by 17.5?
Please help me start the question.
 
Luckygal said:
Mateo and Yvonne are using old records for their mousetrap racers. Mateo is using LPs, which have a diameter of 30cm. His racer's wheels turn 5 times. Yvonne is using 45s, which have a diameter of 17.5cm. Her racer's wheels turn 8.5 times. Who's racer's wheels travels the farthest?

I don't know how to start the equation. Do I divide 5 by 30 and 8.5 by 17.5? Or do I multiply 5 by 30 and 8.5 by 17.5?
Please help me start the question.
Click to expand...

It occurs to me that you may have no idea what a "record" is as they haven't been used in decades. They were circular plastic discs that music was recorded on. That's why it can be imagined using them as wheels.

The racer will travel the circumference of the record used in 1 turn. Recall the formula for the circumference of a circle given it's diameter and you should have all you need to figure this out.
 
Romsek said:
It occurs to me that you may have no idea what a "record" is as they haven't been used in decades.
Click to expand...
I was going to object, but I think you're right.

I'm officially old. :shock: :cry:
 
Luckygal,

Your instinct to either multiply or divide is correct. There is something interesting to learn here. Since one revolution would be the circumfrence of a "record" or wheel, you would use c= 2*pi *r and then multiply by the revolutions of each wheel.

But since you are asked to compare which car went farther and not the actual distance. Comparing 5*30 with 8.5*17.5 is correct as you stated in one of your options to try to solve the problem. Because both numbers are multiplied by a factor of 2*pi.
 
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