If the probability that an event will occur is p and the probability that it will not occur is q, which of the following is true?
A
p-q=1
B
q-p=0
C
p+q=1
D
p+q=0
Verified Correct Answer: C.
Step-by-Step Mathematical Solution
The probability that an event will certainly occur + the probability that an event will certainly not occur =
The probability that an event will certainly occur = 1 - the probability that an event will certainly not occur
The probability that an event will certainly not occur = 1 + The probability that an event will certainly occur
Option C is true.
Source: Myschool Past Questions Archive (Record #26503)