Question 5
A $3\times3$ grid is shown.
Andy wants to shade some cells so that no two shaded cells share an edge. How many ways are there to shade (a) fewer than 3 cells, (b) 3 or 4 cells, (c) more than 4 cells?
Andy wants to shade some cells so that no two shaded cells share an edge. How many ways are there to shade (a) fewer than 3 cells, (b) 3 or 4 cells, (c) more than 4 cells?