A single die is rolled twice. Find the probability of rolling an odd number the first time and a number greater than 4 the second time.

1 answer

To find the probability of rolling an odd number on the first roll of a die and a number greater than 4 on the second roll, we can analyze each event separately since the two rolls are independent.

  1. Rolling an odd number on the first roll: The odd numbers on a standard six-sided die are 1, 3, and 5. Thus, there are 3 odd numbers out of the 6 possible outcomes.

    The probability of rolling an odd number on the first roll is: \[ P(\text{odd first roll}) = \frac{3}{6} = \frac{1}{2} \]

  2. Rolling a number greater than 4 on the second roll: The numbers greater than 4 on a die are 5 and 6. Thus, there are 2 numbers greater than 4 out of the 6 possible outcomes.

    The probability of rolling a number greater than 4 on the second roll is: \[ P(\text{greater than 4 second roll}) = \frac{2}{6} = \frac{1}{3} \]

  3. Calculating the joint probability: Since the two rolls are independent, we can multiply the probabilities of the two events: \[ P(\text{odd first roll and greater than 4 second roll}) = P(\text{odd first roll}) \times P(\text{greater than 4 second roll}) \] \[ = \frac{1}{2} \times \frac{1}{3} = \frac{1}{6} \]

Therefore, the probability of rolling an odd number the first time and a number greater than 4 the second time is \(\boxed{\frac{1}{6}}\).