What is the probability of rolling a 20-sided number cube to a number that is prime or a multiple of 3?

Question

What is the probability of rolling a 20-sided number cube to a number that is prime or a multiple of 3?

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Khoii Minh 4 years 2021-08-24T12:44:45+00:00 2 Answers 9 views 0

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  1. diemthu
    0
    2021-08-24T12:46:03+00:00
    Reply

    Answer:

    Probability of rolling a prime or multiple of 3 = 13/20

    Probability of rolling a prime = 2/5

    Probability of rolling a multiple of 3 = 3/10

    Step-by-step explanation:

    let’s list primes and multiples of 3 from 1 to 20

    Primes:

    2 3 5 7 11 13 17 19

    Multiples of 3:

    3 6 9 12 15 18

    Primes OR multiples of 3

    2 3 5 6 7 9 11 12 13 15 17 18 19

    There’s 13 of them, so the probability of rolling a prime or multiple of 3 is 13/20

    Probability of rolling a multiple of 3 is 6/20 = 3/10

    Probability of rolling a prime is 8/20 = 2/5

  2. taiduc
    0
    2021-08-24T12:46:07+00:00
    Reply

    Answer:

    0.6 or \frac{12}{20} or \frac{3}{5}

    Step-by-step explanation:

    Here are the multiples of 3 (that are 20 or below) :

    • 3
    • 6
    • 9
    • 12
    • 15
    • 18

    Here are the prime numbers (that are 20 or below):

    • 2
    • 3
    • 5
    • 7
    • 11
    • 13
    • 17
    • 19

    Some numbers are repeated in the two lists.

    Here are all the numbers:

    • 2
    • 3
    • 5
    • 6
    • 7
    • 9
    • 11
    • 12
    • 13
    • 15
    • 18
    • 19

    12 numbers are prime or a multiple of 3.

    As a fraction it will be \frac{12}{20}, or simplified to \frac{3}{5}

    As a decimal it will be 0.6

    I hope it helped!

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