Answer:

(1) volume: (1.05× 4 )× (1.05× 3 )×1.05 ≈13.9 (cubic centimeter).

Volume: 4×3× 1= 12 (cubic centimeter)

Note: the size of the box is determined by the outside of the box (the right picture above);

? The size of the box is determined by the inner box part of the box (the left picture above).

(2) The cardboard needed to make this box cover consists of a rectangular cardboard with the length and width of 6cm and 5cm respectively and a rectangular cardboard with the length and width of 4.2cm and 8.4cm respectively.

Board area: 6× 4+(1.05× 4 )× (1.05× 8) = 24+35.28 = 59.28 (square centimeter).

Satisfied with the above answers, please adopt!