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You roll one die 8 times. What is the probability of rolling exactly six fours

2 Answers

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Final answer:

To find the probability of rolling exactly six fours when rolling a die 8 times, we need to use the concept of binomial probability. The probability can be calculated using the formula P(X=k) = nCk * p^k * (1-p)^(n-k), where n is the number of trials, k is the number of successes, and p is the probability of success. Plugging in the values, we can calculate that the probability is approximately 2.6%.

Step-by-step explanation:

To find the probability of rolling exactly six fours when rolling a die 8 times, we need to use the concept of binomial probability.

A binomial probability can be calculated using the formula:

P(X=k) = nCk * p^k * (1-p)^(n-k)

Where:

  • P(X=k) represents the probability of getting exactly k successes
  • n is the number of trials (number of times the die is rolled)
  • k is the number of successes (number of fours we want to roll)
  • p is the probability of getting a success (probability of rolling a four)

In this case, n = 8 (because the die is rolled 8 times), p = 1/6 (because there is one favorable outcome out of 6 possible outcomes), and k = 6 (because we want to roll exactly six fours).

Plugging in these values into the formula, we get:

P(X=6) = 8C6 * (1/6)^6 * (5/6)^(8-6)

To simplify the calculation, we can use the combination formula:

8C6 = 8! / (6!(8-6)!)

Calculating this, we get:

8C6 = 8! / (6! * 2!) = 8 * 7 / 2 = 28

Plugging in this value, along with the probabilities, into the probability formula, we get:

P(X=6) = 28 * (1/6)^6 * (5/6)^2 ≈ 0.026

So, the probability of rolling exactly six fours when rolling a die 8 times is approximately 0.026, or 2.6%.

User Vishal Biradar
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7.8k points
2 votes
1/5 because when you roll 8 times you probraly get 6 more than one time

User The Recruit
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7.5k points
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