SOLUTION: Some children are standing in a circular arrangement. they are evenly spaced and marked in numerical order. the fourth child is standing directly opposite the twelfth child. how ma

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Question 403309: Some children are standing in a circular arrangement. they are evenly spaced and marked in numerical order. the fourth child is standing directly opposite the twelfth child. how many children are in the circle?
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Draw a picture and you'll see that kids #5 through #11 will be in between #4 and #12 (note: we at least know that there are 12 kids). So there are 11-5+1 = 7 kids that are between #4 and #12


So because of symmetry, this means that there must be 7 kids in between kid #12 and kid #4 (say the circle starts at kid #4, so it wraps around back to the kid #4). So add 7 to 12 to get 19. Now realize that there are kids #1, #2, and #3 (which are before #4), so we have to subtract 3 from 19 to get 16 (since we've over counted). So there are 16 kids in the circle.