Question 493480
this is MUCH easier with a Venn Diagram


"5 could operate all 3 machines" ___ 1st group


"8 could operate a lathe and a bender" ___ but 5 of them are from the 1st group, so 3 can operate ONLY lathe and bender
___ 2nd group


"12 could operate a grinder" ___ but 5 of them are from the 1st group, so 7 can operate ONLY a grinder ___ 3rd group


"16 could operate a lathe" ___ but 5 of them are from the 1st group and 3 of them are from the 2nd group
___ so 8 can operate ONLY a lathe ___ 4th group


5 + 3 + 7 + 8 = 23 ___ something is amiss...


no bender or lathe & grinder or bender & grinder?