HPGR test work has been done by two different suppliers on the same feed sample. The sample has a top size of $30$ mm and a d$50$ of $20$ mm $.$ A product d$50$ of $5$ mm is required. The test conditions and results are shown below.

$2\mathrm{.}1$ What is the difference in the machines offered by the two suppliers?

$2\mathrm{.}2$ Whose machine is more efficient.