$.$

$$A TSA officer verifying ID and boarding pass

$2$

$.$

$$Searching the passenger for metal objects

$($

security scan

$)$

The passenger is going through a metal detector, which is staffed with another designated TSA officer who watches the screen and performs the pat

$-$

down search if needed

$3$

$.$

$$Running the carry

$-$

on luggage through X

$-$

ray machine

There is a long line of passengers before the first step, but sometimes lines also build up at steps

$2$

$$and

$3$

$.$

$$Step

$2$

$$and

$3$

$$are parallel; that is customers go through the metal detector while their luggage is in the X

$-$

ray machine.

The first step, verifying ID and boarding pass, takes

$3$

$0$

$$seconds per passenger. The second step, searching the passenger for metal objects using a metal detector, takes

$1$

$0$

$$seconds per passenger. The third step, running the carry

$-$

on luggage through an X

$-$

ray machine, takes

$6$

$0$

$$seconds per passenger.

The airport instialls two more x ray machines so that now a tatal of three x ray machines work in parallel what is the new capcxity of the porocess express in passengers per minute