A grocery store buys cereal using the cost function
\( c ( n ) = \{ \)
\( 2 n \) when \( n < 100 \)
\( 1.9 n \) when \( 100 \leq n \leq 500 \)
\( 1.8 n \) when \( n > 500 \)
where \( n \) is the number of boxes of cereal the grocery store buys and \( c ( n ) \) is the cost of the cereal. The grocery store then sells the cereal using the sales function \( s ( c ) = 1.3 c \) . What is the cost of the cereal if the grocery store buys \( 250 \) boxes?
\( 617.5\)