If a die is rolled one time, find the probability of getting a number less than 4 or an even number.
A)1/6
B)1
C)5/6
D)0

Question

Quizplus · Accepted Answer

Getting a number less than 4: There are 3 possible outcomes (1, 2, 3) out of 6 total outcomes, so the probability is 3/6 or 1/2.
Getting an even number: There are 3 possible outcomes (2, 4, 6) out of 6 total outcomes, so the probability is 3/6 or 1/2.
To find the probability of either event happening, we add the probabilities of each event happening and subtract the probability of both events happening at once (because that would be counted twice). So, the probability is:
P(number less than 4 or even) = P(number less than 4) + P(even) - P(less than 4 and even)
P(number less than 4 or even) = 1/2 + 1/2 - 1/3
P(number less than 4 or even) = 5/6
Therefore, the best choice is C. Getting a number less than 4 includes rolling a 1, 2, or 3, which has a probability of 3/6 or 1/2. Rolling an even number includes rolling a 2, 4 or 6, which also has a probability of 3/6 or 1/2. To find the probability of getting either of these outcomes, we add the probabilities together:

P(number less than 4 or an even number) = P(number less than 4) + P(even number) 
= 1/2 + 1/2 
= 1

Therefore, the probability of getting a number less than 4 or an even number when rolling a die one time is 1, which corresponds to choice C.

If a Die Is Rolled One Time, Find the Probability