Random(0,15) generates a number from 0 to up to 15, but not 15.
With floor, he makes this random number an integer.
You could use this, with Floor(Random(45)) -> this will generate an integer between 0 and 44.
Generate 30 of these.
After that, loop through the array, and base on what the value of the array -> create your object.
Generate different object based on all the random value could be in the array