(1) Every time the selling price increases by 2 yuan, four pieces are sold less, that is, every time the selling price increases by 0.5 yuan. Sell less 1 block.

Therefore, 9.5 yuan sells less 1 piece than 9 yuan, that is, it sells 5 pieces.

(2) Set the sales price of X yuan.

The sales volume is 6-(x-3)/0.5.

Profit per piece x-2.

Then (x-2) * (18-(x-3)/0.5) = 48.

X = 8 yuan or X = 6 yuan.