answer is 5000 resistors, the quesiton never said that they had to deliver working resistors
but if you wanted 5000 working resistors the rest is working 100%=all all-defective=working 100-4=96 96%=working working=5000 find 100% 96%ofall=5000 percent means parts out of 100 96/100ofall=5000 times both sides by 100 96ofall=500000 divide both sides by 96 all=5028.33333 round up 5029 resistors must be made to deliver at least 5000 working ones
