To find the cube root of a number means to find what number can be multiplied by itself three times to equal the original number. Example: The cube root of 8 is 2 because 2 x 2 x 2 = 8. Hope this helped :)
It would serve 5.3 people, or just 5 because you can't have .3 of a person. This is because 9/4=12/x so 9x=48, and 48 divided by 9 is 5.3, or just 5 people.