Question

A dice is thrown once
A = {Getting 1,2,3,4 or 5}
B = {Getting 4 or 5}
Then complement of B =

• A. {1, 2, 3}
• B. {1, 2, 3, 6}
• C. {1, 2, 3, 4, 5}
• D. {1, 2, 4}

Answer 1

The correct option is B {1, 2, 3, 6}

Sample space for the dice thrown once = {1,2,3,4,5,6}
B = {4,5}
So B’ = S - B
= {1,2,3,4,5,6} - {4,5}
= {1,2,3,6}
Please note that complement of an event is not defined with respect to some other event. It is only with respect to sample space. So, elements of the event B are to be subtracted from sample space and not from A.