Can someone explain to me how to answer questions like this? I always get confused!
1 answer:
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Complete question is;
After examining daily receipts over the past year, it was found that the green parrot italian restaurant has been grossing over $2200 a day for about 85% of it's business days. Using this as a reasonably accurate measure, find the probability that the green parrot will gross over $2200:
A. At least 5 of the next 7 business days.
B. at least 5 of the next 10 business days.
C. less than 3 of the next 5 business days.
d. Exactly 7 of the next 10 business days
e. At least 1 of the next 5 business days.
Answer:
A) P(X ≥ 5) = 0.9262
B) P(X ≥ 5) = 0.9986
C) P(X ≤ 2) = 0.0266
D) P(X = 7) = 0.1298
E) P(X ≥ 1) = 0.9999
Step-by-step explanation:
This is a binomial probability distribution problem and as such we will use the formula;
P(X = k) = C(n, k) × p^(k) × (1 - p)^(n - k)
A. At least 5 of the next 7 business days will be;
P (X ≥ 5) = P(X = 5) + P(X = 6) + P(X = 7)
P(X = 5) = C(7, 5) × 0.85^(5) × (1 - 0.85)^(7 - 5)
P(X = 5) = 0.20965
P(X = 6) = C(7, 6) × 0.85^(6) × (1 - 0.85)^(7 - 6)
P(X = 6) = 0.396
P(X = 7) = C(7, 7) × 0.85^(7) × (1 - 0.85)^(7 - 7)
P(X = 7) = 0.320577
Thus;
P(X ≥ 5) = 0.20965 + 0.396 + 0.320577
P(X ≥ 5) = 0.9262
B. Probability of at least 5 of the next 10 business days will be;
P(X ≥ 5) = P(X = 5) + P(X = 6) + P(X = 7) + P(X = 8) + P(X = 9) + P(X = 10)
From online binomial calculator attached, we can see that the answer is;
P(X ≥ 5) = 0.9986
C. Probability of less than 3 of the next 5 business days will be;
P(X ≤ 2) = P(X = 0) + P(X = 1) + P(X = 2)
From online binomial calculator attached, we can see that the answer is;
P(X ≤ 2) = 0.0266
D. Probability of exactly 7 of the next 10 business days will be;
P(X = 7) = C(10, 7) × 0.85^(7) × (1 - 0.85)^(10 - 7)
P(X = 7) = 0.1298
e. Probability of at least 1 of the next 5 business days will be;
P(X ≥ 1) = P(X = 1) + P(X = 2) + P(X = 3) + P(X = 4) + P(X = 5)
From third image attached using online binomial calculator, we have;
P(X ≥ 1) = 0.9999
