These are 30 objects,, and each object has 2
options i.e, either go in box A or in box 13.
Hence Total ways = 2×2×−−−30 times=230
Now in these 230 ways, these would be one
particular instance when all objects would have gone to box A.
Also, there be one particular instance when all object would have gone to box B.
so these are 2 instance when one of the box would have been empty.
⇒ Required number of ways =230−2