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Multiple Choice
A student working on a transportation engineering project analyzes traffic flow at an intersection for 20 min. From past data, the average # of cars per minute is 17.6. (B) Find the probability that the student observes 350 or more cars total.
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검증된 단계별 안내
1
Step 1: Recognize that the problem involves a Poisson distribution, as it deals with the number of cars arriving at an intersection over a fixed time interval. The average rate (λ) is given as 17.6 cars per minute, and the total observation time is 20 minutes.
Step 2: Calculate the expected total number of cars over 20 minutes. Multiply the average rate per minute (λ = 17.6) by the total time (20 minutes). This gives the mean (μ) of the Poisson distribution for the total number of cars.
Step 3: Since the Poisson distribution can be approximated by a normal distribution for large values of λ, use the normal approximation. The mean (μ) is the expected total number of cars, and the standard deviation (σ) is the square root of the mean: σ = √μ.
Step 4: Standardize the value 350 using the z-score formula: z = (X - μ) / σ, where X is the observed value (350), μ is the mean, and σ is the standard deviation. This converts the problem into finding the probability under the standard normal distribution.
Step 5: Use standard normal distribution tables or software to find the probability corresponding to the z-score. Since the problem asks for the probability of observing 350 or more cars, calculate the area to the right of the z-score (1 - P(Z ≤ z)).