math
posted by Anonymous .
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 only 1 interaction.
If there are 3 children, there can be 4 interactions.
If there are 4 children, there can be 9 interactions.
How many interactions will there be for 8 children?

Are they implying that interaction (I) between children (c) is a quadratic function ????
then
I(c)= (c1)^2
so I(8) = 7^2 = 49
(look like a textbook editor's feeble attempt to "make mathematics real" ) 
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?
60
81
105
108 
105