1 m =3 feet

1 ft = 10 inch

1 inch ≈3.33 cm.

So: 10 inch cake is about 33.3 cm in diameter, 12 inch cake is about 40 cm in diameter, and 14 inch cake is about 46.7 cm in diameter.

According to the number of people, there are a lot of eight adults and four children, so it is better to eat 14 inch cake.