Machine learning is a tool for solving problems. However, not all problems can be solved using it$.$ Which of the following problems are best solved with machine learning:

$1.$Determining if a number is prime or not?

$2.$identifying malicious activities in a computer network?

$3.$Determining the name and position of an employee based on his ID$?$

$4.$Determining the ethnicity of a person based on his$/$her picture?