Not sure what to do to show my work for this probability question?
In a recent survey, only 47% of Americans had a three-day supply of bottled water in case of emergency. Suppose a sample of 35 Americans is selected at random.
a. What is the probability that exactly 12 Americans have a three-day supply of bottled water on hand?
b. What is the probability that at least 18 Americans have a three-day supply of bottled water on hand?
- PuzzlingLv 710 months agoFavorite Answer
Use the binomial probability formula.
P(X = k) = C(n, k) * p^k * q^(n - k)
n : number of trials (35)
k : number of successes (12)
p : probability of success (0.47)
q : probability of failure (1-p = 0.53)
P(X = 12) = C(35, 12) * 0.47^12 * 0.53^23
As for at least 18, you'd want to calculate the probability of 18 and above.
P(X = 18) = 0.116755
P(X > 18) = 0.243480
P(X ≥ 18) = 0.360135