Probability

[davidleung808]

A 6-sided die is rolled. What is the probability that the value of the roll either an odd number or else exactly 4?

 

[Dr.Peterson]

List all the possibilities, and mark those that are either odd or 4. How many are there?

 

[davidleung808]

Dr. Peterson,

I find the probability that either of these mutually exclusive events will occurs by adding their individual probabilities.

P(odd or exactly 4) = (3/6) + (1/6) = (4/6) = 2/3

The probability of selecting an odd or else exactly 4 = 2/3. Am I correct?

 

[Dr.Peterson]

A 6-sided die is rolled. What is the probability that the value of the roll either an odd number or else exactly 4?

Here are the six possible outcomes, with odd numbers in bold and 4 underlined: 1 2 3 4 5 6

Thus 4 outcomes out of 6 are "either odd or exactly 4", and the probability is 2/3. That's the simple method I suggested.

I find the probability that either of these mutually exclusive events will occur by adding their individual probabilities.

P(odd or exactly 4) = (3/6) + (1/6) = (4/6) = 2/3

The probability of selecting an odd or else exactly 4 = 2/3. Am I correct?

Since you have learned about mutual exclusivity and the formula for "or" probabilities in that case, the method you used is more appropriate. (Since you'd shown no work, I couldn't tell what methods were available.)

Both ways, of course, give the same (correct) answer.