Your teacher puts numbers 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 and 12 in a hat and asks you to draw a number. What's the probability that you will draw either a 4 or a 6?
A
1
1
2
12
1
B
2
1
2
12
2
C
4
1
2
12
4
D
6
1
2
12
6
C. The probability of drawing either a 4 or a 6 is calculated by adding the individual probabilities of drawing a 4 and drawing a 6, and then subtracting the probability of drawing both a 4 and a 6 (as that would be double counted).
Probability of drawing a 4 = 1/12
Probability of drawing a 6 = 1/12
Probability of drawing both a 4 and a 6 = 0
Therefore, probability of drawing either a 4 or a 6 = 1/12 + 1/12 - 0 = 2/12 = 1/6.