Mathematics for IGCSE & O level - Probability (Section 6 - No. 11)
A bag contains 5 red and 5 blue marbles. What is the probability of selecting a red marble *or* a blue marble?
0
0.25
0.5
1
Giải thích
All marbles are either red or blue. So probability is 1 (or 10/10 = 1).