My team’s teacher told if where is way will inflate the cargo to the right psi to get 13 inches.
It likely depends on the amount of usage of the ball, possibly even the batch it was produced in. These balls are not scientific instruments, and were not designed or manufactured to inflate to a consistent dimension with a consistent pressure.
The problem with this practice is that the ball stretches over time, so there is no static PSI where it will reach the right diameter.
I recommend you make some sizing jigs like spectrum did here to make sure they are roughly the right size.
This was asked, and answered, on the Q&A:
No, per Section 4.9.1, they are inflated to a size specification. No psi specification is defined.
I observed PSI while inflating the ball. PSI remained fairly constant, and the size continued to grow. Inflate by size.