Math Problem Statement

When purchasing bulk orders of​ batteries, a toy manufacturer uses this acceptance sampling​ plan: Randomly select and test 46 batteries and determine whether each is within specifications. The entire shipment is accepted if at most 3 batteries do not meet specifications. A shipment contains 6000 ​batteries, and 1​% of them do not meet specifications. What is the probability that this whole shipment will be​ accepted? Will almost all such shipments be​ accepted, or will many be​ rejected?

Solution

We can model this situation as a hypergeometric distribution problem since we are sampling without replacement from a finite population of 6000 batteries, and the batteries are either "defective" (not meeting specifications) or "good."

Step-by-step breakdown:

  1. Population size (NN): 6000 batteries in the shipment.
  2. Number of defective batteries (DD): 1% of 6000 batteries are defective, so: D=6000×0.01=60 defective batteries.D = 6000 \times 0.01 = 60 \text{ defective batteries}.
  3. Sample size (nn): 46 batteries are tested.
  4. Acceptable defective count: The shipment is accepted if at most 3 defective batteries are found in the sample of 46.

We want to calculate the probability that the shipment is accepted, which means that 3 or fewer defective batteries are found in the sample of 46. This can be calculated using the hypergeometric probability formula:

P(X=k)=(Dk)(NDnk)(Nn)P(X = k) = \frac{\binom{D}{k} \binom{N-D}{n-k}}{\binom{N}{n}} where:

  • DD is the number of defective batteries in the population,
  • NN is the total population size (6000),
  • nn is the sample size (46),
  • kk is the number of defective batteries found in the sample,
  • (ab)\binom{a}{b} is the binomial coefficient "a choose b."

To find the total probability:

We need to sum the probabilities for k=0k = 0, k=1k = 1, k=2k = 2, and k=3k = 3:

P(shipment accepted)=P(X=0)+P(X=1)+P(X=2)+P(X=3)P(\text{shipment accepted}) = P(X = 0) + P(X = 1) + P(X = 2) + P(X = 3)

This requires calculating each term individually:

P(X=0)=(600)(594046)(600046)P(X = 0) = \frac{\binom{60}{0} \binom{5940}{46}}{\binom{6000}{46}} P(X=1)=(601)(594045)(600046)P(X = 1) = \frac{\binom{60}{1} \binom{5940}{45}}{\binom{6000}{46}} P(X=2)=(602)(594044)(600046)P(X = 2) = \frac{\binom{60}{2} \binom{5940}{44}}{\binom{6000}{46}} P(X=3)=(603)(594043)(600046)P(X = 3) = \frac{\binom{60}{3} \binom{5940}{43}}{\binom{6000}{46}}

Will almost all shipments be accepted or rejected?

To answer this question, we must compute the above probabilities and sum them up. If the result is a high probability (close to 1), then almost all shipments will be accepted. If the probability is lower, many shipments will be rejected.

Would you like me to perform the calculations for each term, or do you need any further clarification?


Here are 5 relative questions to expand on this problem:

  1. What is the general difference between binomial and hypergeometric distributions?
  2. How would this problem change if sampling were with replacement?
  3. What if the acceptable number of defective batteries was raised to 5? How would the probability change?
  4. How does the sample size (46) affect the accuracy of acceptance sampling?
  5. What is the impact of increasing the population size (e.g., 10,000 batteries) on the acceptance probability?

Tip: Hypergeometric distributions are often used when the population is relatively small and sampling is done without replacement, making them ideal for quality control problems like this one.

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Math Problem Analysis

Mathematical Concepts

Probability
Hypergeometric Distribution
Quality Control Sampling

Formulas

P(X = k) = (C(D, k) * C(N-D, n-k)) / C(N, n)

Theorems

Hypergeometric Distribution Theorem

Suitable Grade Level

College Level (Statistics/Probability)