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Mr. and Mrs. Doran have a genetic history such that the probability that a child being born to them with a certain trait is 
2//3. If they have five children, what is the probability that at least four of their five children will have that trait? Round your answer to the nearest thousandth.
Answer:

Mr. and Mrs. Doran have a genetic history such that the probability that a child being born to them with a certain trait is 2/3 2 / 3 . If they have five children, what is the probability that at least four of their five children will have that trait? Round your answer to the nearest thousandth.\newlineAnswer:

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Q. Mr. and Mrs. Doran have a genetic history such that the probability that a child being born to them with a certain trait is 2/3 2 / 3 . If they have five children, what is the probability that at least four of their five children will have that trait? Round your answer to the nearest thousandth.\newlineAnswer:
  1. Identify values for formula: Identify the values of nn, kk, and pp for the binomial probability formula.\newlinen=5n = 5 (the number of children)\newlinep=23p = \frac{2}{3} (the probability of a child having the trait)\newlineWe want to find the probability of at least four children having the trait, so we need to calculate the probability for k=4k = 4 and k=5k = 5.
  2. Use binomial probability formula: Use the binomial probability formula for k=4k = 4.P(X=k)=C(n,k)(p)k(1p)(nk)P(X = k) = C(n, k) \cdot (p)^k \cdot (1-p)^{(n-k)}Substitute n=5n = 5, k=4k = 4, and p=23p = \frac{2}{3} into the formula.P(X=4)=C(5,4)(23)4(123)(54)P(X = 4) = C(5, 4) \cdot \left(\frac{2}{3}\right)^4 \cdot \left(1 - \frac{2}{3}\right)^{(5 - 4)}
  3. Calculate binomial coefficient: Calculate the binomial coefficient C(5,4)C(5, 4).C(5,4)=5!4!(54)!C(5, 4) = \frac{5!}{4!(5 - 4)!}C(5,4)=51C(5, 4) = \frac{5}{1}C(5,4)=5C(5, 4) = 5
  4. Calculate (2/3)4(2/3)^4: Calculate (2/3)4(2/3)^4.
    (2/3)4=(2/3)×(2/3)×(2/3)×(2/3)(2/3)^4 = (2/3) \times (2/3) \times (2/3) \times (2/3)
    (2/3)4=16/81(2/3)^4 = 16/81
  5. Calculate (123)(54)(1 - \frac{2}{3})^{(5 - 4)}: Calculate (123)(54)(1 - \frac{2}{3})^{(5 - 4)}.(123)(54)=(13)1(1 - \frac{2}{3})^{(5 - 4)} = (\frac{1}{3})^1(123)(54)=13(1 - \frac{2}{3})^{(5 - 4)} = \frac{1}{3}
  6. Calculate P(X=4)P(X = 4): Calculate P(X=4)P(X = 4).P(X=4)=5×(1681)×(13)P(X = 4) = 5 \times \left(\frac{16}{81}\right) \times \left(\frac{1}{3}\right)P(X=4)=5×(1681)×(13)P(X = 4) = 5 \times \left(\frac{16}{81}\right) \times \left(\frac{1}{3}\right)P(X=4)=80243P(X = 4) = \frac{80}{243}
  7. Use binomial probability formula: Use the binomial probability formula for k=5k = 5.
    P(X=5)=C(5,5)(23)5(123)(55)P(X = 5) = C(5, 5) \cdot \left(\frac{2}{3}\right)^5 \cdot \left(1 - \frac{2}{3}\right)^{(5 - 5)}
    Substitute n=5n = 5, k=5k = 5, and p=23p = \frac{2}{3} into the formula.
    P(X=5)=C(5,5)(23)5(123)(0)P(X = 5) = C(5, 5) \cdot \left(\frac{2}{3}\right)^5 \cdot \left(1 - \frac{2}{3}\right)^{(0)}
  8. Calculate binomial coefficient: Calculate the binomial coefficient C(5,5)C(5, 5).C(5,5)=5!5!(55)!C(5, 5) = \frac{5!}{5!(5 - 5)!}C(5,5)=11C(5, 5) = \frac{1}{1}C(5,5)=1C(5, 5) = 1
  9. Calculate (2/3)5(2/3)^5: Calculate (2/3)5(2/3)^5.
    (2/3)5=(2/3)×(2/3)×(2/3)×(2/3)×(2/3)(2/3)^5 = (2/3) \times (2/3) \times (2/3) \times (2/3) \times (2/3)
    (2/3)5=32/243(2/3)^5 = 32/243
  10. Calculate (123)(55)(1 - \frac{2}{3})^{(5 - 5)}: Calculate (123)(55)(1 - \frac{2}{3})^{(5 - 5)}.\newline(123)(55)=(13)0(1 - \frac{2}{3})^{(5 - 5)} = (\frac{1}{3})^0\newline(123)(55)=1(1 - \frac{2}{3})^{(5 - 5)} = 1
  11. Calculate P(X=5)P(X = 5): Calculate P(X=5)P(X = 5).P(X=5)=1×(32243)×1P(X = 5) = 1 \times \left(\frac{32}{243}\right) \times 1P(X=5)=32243P(X = 5) = \frac{32}{243}
  12. Calculate probability of at least four children: Calculate the probability of at least four children having the trait.\newlineThis is the sum of the probabilities for k=4k = 4 and k=5k = 5.\newlineP(at least 4)=P(X=4)+P(X=5)P(\text{at least 4}) = P(X = 4) + P(X = 5)\newlineP(at least 4)=80243+32243P(\text{at least 4}) = \frac{80}{243} + \frac{32}{243}\newlineP(at least 4)=112243P(\text{at least 4}) = \frac{112}{243}
  13. Convert probability to decimal: Convert the probability to a decimal and round to the nearest thousandth.\newlineP(at least 4)=112243P(\text{at least } 4) = \frac{112}{243}\newlineP(at least 4)0.461P(\text{at least } 4) \approx 0.461

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