56% of students in a class have black hair. If 5 students are chosen at random, what is the probability that exactly 2 have black hair? Write your answer as a decimal rounded to the nearest thousandth. ____
Q. 56% of students in a class have black hair. If 5 students are chosen at random, what is the probability that exactly 2 have black hair? Write your answer as a decimal rounded to the nearest thousandth. ____
Calculate Probability of Black Hair: First, we need to calculate the probability of one student having black hair, which is 56%, or 0.56 in decimal form.
Use Binomial Probability Formula: Now, we use the binomial probability formula, which is P(X=k)=(kn)⋅(pk)⋅((1−p)n−k), where n is the number of trials, k is the number of successes, p is the probability of success on a single trial, and (kn) is the binomial coefficient.
Identify Parameters: Here, n=5 (number of students chosen), k=2 (number of students with black hair we want), and p=0.56 (probability of a student having black hair).
Calculate Binomial Coefficient: Calculate the binomial coefficient (25), which is 2!⋅(5−2)!5!. That's 2⋅15⋅4=10.
Calculate pk: Now, calculate pk, which is 0.562. That's about 0.3136.
Calculate (1−p)(n−k): Next, calculate (1−p)(n−k), which is (1−0.56)(5−2). That's 0.443, which is about 0.085184.
Multiply All Calculations: Multiply all these together: 10×0.3136×0.085184. That's about 0.2668.
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