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If a fair die is rolled 7 times, what is the probability, to the nearest thousandth, of getting exactly 1 two?
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If a fair die is rolled 77 times, what is the probability, to the nearest thousandth, of getting exactly 11 two?\newlineAnswer:

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Q. If a fair die is rolled 77 times, what is the probability, to the nearest thousandth, of getting exactly 11 two?\newlineAnswer:
  1. Determine Probability of Two: Determine the probability of rolling a two on a single roll of a fair die. A fair die has six faces, so the probability of rolling any specific number, including a two, is 11 out of 66.
  2. Determine Probability of Not Two: Determine the probability of not rolling a two on a single roll of a fair die. Since there are 55 other outcomes that are not a two, the probability of not rolling a two is 56\frac{5}{6}.
  3. Calculate Probability of One Two in Seven Rolls: Calculate the probability of rolling exactly one two in seven rolls.\newlineThis event can happen in several different ways: the two can appear on the first roll, the second roll, and so on, up to the seventh roll. For each case, the other six rolls must not be a two.
  4. Use Binomial Probability Formula: Use the binomial probability formula to calculate the probability of exactly one success (rolling a two) in seven trials (rolls).\newlineThe binomial probability formula is P(X=k)=(nk)(pk)((1p)(nk))P(X=k) = \binom{n}{k} \cdot (p^k) \cdot ((1-p)^{(n-k)}), where:\newline- P(X=k)P(X=k) is the probability of kk successes in nn trials,\newline- (nk)\binom{n}{k} is the binomial coefficient,\newline- pp is the probability of success on a single trial,\newline- (1p)(1-p) is the probability of failure on a single trial.
  5. Plug Values into Formula: Plug the values into the binomial probability formula.\newlineHere, n=7n=7 (number of trials), k=1k=1 (number of successes), p=16p=\frac{1}{6} (probability of rolling a two), and (1p)=56(1-p)=\frac{5}{6} (probability of not rolling a two).\newlineP(X=1)=(71)×(16)1×(56)71P(X=1) = \binom{7}{1} \times \left(\frac{1}{6}\right)^1 \times \left(\frac{5}{6}\right)^{7-1}
  6. Calculate Binomial Coefficient: Calculate the binomial coefficient (71)\binom{7}{1}.(71)\binom{7}{1} is the number of ways to choose 11 success (rolling a two) out of 77 trials, which is simply 77.
  7. Perform Calculations: Perform the calculations.\newlineP(X=1)=7×(16)1×(56)6P(X=1) = 7 \times \left(\frac{1}{6}\right)^1 \times \left(\frac{5}{6}\right)^6\newlineP(X=1)=7×(16)×(56)6P(X=1) = 7 \times \left(\frac{1}{6}\right) \times \left(\frac{5}{6}\right)^6
  8. Calculate Exact Probability: Calculate the exact probability.\newlineP(X=1)=7×(16)×(1562546656)P(X=1) = 7 \times \left(\frac{1}{6}\right) \times \left(\frac{15625}{46656}\right) (since (56)6=1562546656\left(\frac{5}{6}\right)^6 = \frac{15625}{46656})\newlineP(X=1)=7×(16)×(1562546656)P(X=1) = 7 \times \left(\frac{1}{6}\right) \times \left(\frac{15625}{46656}\right)\newlineP(X=1)=7×156256×46656P(X=1) = 7 \times \frac{15625}{6 \times 46656}\newlineP(X=1)=109375279936P(X=1) = \frac{109375}{279936}
  9. Simplify Fraction and Round: Simplify the fraction and round to the nearest thousandth. P(X=1)0.391P(X=1) \approx 0.391 (rounded to three decimal places)

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