$\backslash$table$[[\backslash$table$[[$Number of$],[$Workers$]],\backslash$table$[[$Output $($number$],[$of students tutored$],[$per week$)]]],[0,0],[1,20],[2,45],[3,60],[4,70]]$

Refer to Table $13-4.$ What is the marginal product of the second worker?

$15$ students

$20$ students

$22\mathrm{.}5$ students

$25$ students