Question

Student is told that A union B is the set of all elements that beling to A or B. However when askef to find the union of A{a,b,c,d}, and B{c,d,e,f,g,h} the student say that the answer is {a,b,e,f g,h}. How is the word or in the definition of set of union being misunderstood

Answer 1

He interprets the word 'or'  to mean that if both sets contain a common element they are not included in the union. That is why he has not included c and d