If approximately 12.3% of American high school students drop out of school before graduation, assuming that the variable is binomial and choosing 14 students entering high school at random, the probability that all 14 stay in school and graduate is 0.160
As per the question statement, approximately 12.3% of American high school students drop out of school before graduation, and assuming that the variable is binomial, we are choosing 14 students entering high school at random.
We are required to calculate the probability that all 14 stay in school and graduate.
Given, Drop-out percentage = 12.3,
i.e., Drop-out Probability = (12.3/100) = 0.123
Therefore, Graduate Probability = (1 - 0.123) = 0.877
Let, the Drop-out and Graduate Probabilities be denoted by two random variables, "q" and "p" respectively. Then, (p = 0.877) and (q = 0.123).
Now, P (all 14 staying in school and graduating) = P(X = 14)
And, using binomial distribution, we can write that,
[tex]P(X = r) = [\frac{N!}{r!(N - r)!}*p^{r} *q^{N-r}][/tex]
Here, (r = 14), (X = 14), (p = 0.877) and (q = 0.123). Substituting these values in the above-mentioned formula, we get,
[tex]P(X = 14) = [\frac{14!}{14!(14 - 14)!}*0.877^{14} *0.123^{(14-14)}]\\Or, P(X = 14) = [\frac{14!}{14!0!}*0.877^{14} *0.123^{0}]\\[/tex]
Or, P(X = 14) = {(14!)/(14! * 1)} * 0.877¹⁴ * 1
Or, P(X = 14) = [(14!)/(14!)] * 0.877¹⁴
Or, P(X = 14) = 1 * 0.877¹⁴
Or, P(X = 14) = 0.159219
Or, (PX = 14) ≈ 0.160
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