statistics problem due in 1hr from now

A toddlers-toy is to be mass-produced. It consists of a bracket and four cubes. You get the
dimensions below. 

1: What should the value of the holder length indicate so that of at least 99.97% of all the picking boxes shall be accepted? If the tolerance is greater than 0.5 mm, it is still acceptable but the cubes should still be able to get down in the holder.


2: How many of picking boxes will be accepted if the length of the holder is set to 
200.0 mm?


3: If the length of the holder is more than 1 mm longer than the total length of the cubes 
the cubes will rattle (they will not lie still) in the holder. How many picking boxes will have to be discarded? 

4: Can you in any way affect so you do not have to discard as many picking boxes?

Here is the actual problem with picture so you can understand better.

http://imgur.com/HsKuiuA

need it within 45minutes from now this is 10-15 work only