Answer:
'A or B' Â = Â {1,2,3,4,6,8}
'A and  B'  =   {2}
The complement of A Â = Â {4,5,6,7,8)
Step-by-step explanation:
Here, the sample space of possible outcomes = { 1,2,3,4,5,6,7,8}
Event A: The marble selected has a number of less than 4
So, favorable outcomes here= Â {1,2,3)
Event B: The marble selected has an even number.
So, favorable outcomes here= Â {2,4,6,8)
Total number of outcomes in Event 'A or B' = Â A U B Â = Â {1,2,3,4,6,8}
⇒ 'A or B'  =  {1,2,3,4,6,8}
Total number of outcomes in Event 'A and  B' =  A ∩ B  =  {2}
⇒ 'A and  B'  =   {2}
Now, The complement of A  = Sample Space  - Element in A
                         = {4,5,6,7,8}
⇒The complement of A  =  {4,5,6,7,8)