Pine cones are evenly spaced on a circular wreath. The third pine cone is opposite the ninth pine cone.?

How many pine cones are on the wreath?





This is my sisters math problem that she can't figure out. That's how its written in the book. I'm thinking they didn't give enough information. Any help is appreciated. Thanks

Pine cones are evenly spaced on a circular wreath. The third pine cone is opposite the ninth pine cone.?
The third cone is opposite the ninthe cone it means if we join the third and the ninth cone , a diameter of the circle would be formed.





Between 3'rd and 9'th cones there are 5 cones on each semi circle.





So total no of cones = 2+5+5 = 12
Reply:Think of a clock(or go look at one). Aren't 3 and 9 opposite each other? since there are 12 numbers on a clock, there are 12 pine cones on the wreath.
Reply:If cones are evenly spaced and you have two that are across from each other, then if you draw a line between the two, you should have the same number of cones on either side of the line. In between cones #3 and #9, you have cones #4, 5, 6, 7, and 8. This means you must have five cones in between #9 and #3. So the total number of comes is 5 plus 5 plus the two cones on the line (3 and 9), giving you 12.





You could have also noticed that 3 and 9 are opposite on a clock face, and there are 12 numbers on a clock. But the same reasoning applies.