a 12 sided die is rolled find the probability of rolling a number greater than 7

Discussion in 'Calculator Requests' started by math_celebrity, Oct 18, 2021.

  1. math_celebrity

    math_celebrity Administrator Staff Member

    a 12 sided die is rolled find the probability of rolling a number greater than 7

    We assume this is a fair die, not loaded.

    This means each side 1-12 has an equal probability of 1/12 of being rolled.

    The problem asks, P(Roll > 7)
    Greater than 7 means our sample space is {8, 9, 10, 11, 12}

    If each of these 5 faces have an equal probability of being rolled, then we have:
    P(Roll > 7) = P(Roll = 8) + P(Roll = 9) + P(Roll = 10) + P(Roll = 11) + P(Roll = 12)
    P(Roll > 7) = 1/12 + 1/12 + 1/12 + 1/12 + 1/12
    P(Roll > 7) = 5/12
     

Share This Page