Question 599525
A playground is being designed where children can interact with their friends in certain combinations. 
If there is 1 child, there can be 0 interactions. 
If there are 2 children, there can be 6 interactions. 
If there are 3 children, there can be 15 interactions. 
If there are 4 children, there can be 27 interactions. 
How many interactions will there be for 7 children? 
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I ran a Quadratic Regression program on the data and got
the following formula:
y = (3/2)x^2 + (3/2)x -3
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f(7) = 81
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Cheers,
Stan H.