Math Problem Statement

A pharmaceutical company receives large shipments of ibuprofen tablets and uses this acceptance sampling plan: randomly select and test 22 tablets, then accept the whole batch if there is at most one that doesn't meet the required specifications. If a particular shipment of thousands of ibuprofen tablets actually has a 2% rate of defects, what is the probability that this whole shipment will be accepted?

(Report answer as a decimal value accurate to four decimal places.) P(accept shipment) = 

Solution

We define the random variable XX as the number of defective tablets in a sample of 22 tablets. Since each tablet is either defective or not, and the probability of a defective tablet is 2% (0.02), we model XX using the binomial distribution:

XBinomial(n=22,p=0.02)X \sim \text{Binomial}(n=22, p=0.02)

The shipment is accepted if at most 1 defective tablet is found, meaning we need to calculate:

P(X1)=P(X=0)+P(X=1)P(X \leq 1) = P(X = 0) + P(X = 1)

Using the binomial probability mass function:

P(X=k)=(nk)pk(1p)nkP(X = k) = \binom{n}{k} p^k (1-p)^{n-k}

we calculate:

  1. For X=0X = 0: P(X=0)=(220)(0.02)0(0.98)22P(X = 0) = \binom{22}{0} (0.02)^0 (0.98)^{22} =(1)(1)(0.98)22= (1)(1)(0.98)^{22}

  2. For X=1X = 1: P(X=1)=(221)(0.02)1(0.98)21P(X = 1) = \binom{22}{1} (0.02)^1 (0.98)^{21} =22(0.02)(0.98)21= 22 \cdot (0.02) \cdot (0.98)^{21}

Now, we compute the values numerically. math import comb

Given values

n = 22 # sample size p = 0.02 # probability of defect q = 1 - p # probability of non-defect

Compute probabilities

P_X_0 = comb(n, 0) * (p ** 0) * (q ** 22) P_X_1 = comb(n, 1) * (p ** 1) * (q ** 21)

Total probability of acceptance

P_accept = P_X_0 + P_X_1 P_acceptThe probability that the whole shipment will be accepted is 0.9290 (rounded to four decimal places).

Would you like a more detailed explanation of the calculations? Here are some related questions:

  1. How does the binomial distribution apply to quality control in pharmaceutical companies?
  2. What happens to the acceptance probability if the defect rate increases to 5%?
  3. How would this probability change if the sample size were increased to 30 tablets?
  4. What is the probability of rejecting the shipment instead?
  5. How could a company improve its sampling strategy to reduce the chance of accepting bad shipments?

Tip:

When using the binomial distribution for small defect probabilities, the Poisson approximation can sometimes simplify calculations!

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Binomial Distribution
Probability Theory
Combinatorics

Formulas

Binomial Probability Mass Function: P(X = k) = C(n, k) * p^k * (1-p)^(n-k)
P(X ≤ 1) = P(X = 0) + P(X = 1)

Theorems

Binomial Distribution Theorem
Binomial Coefficient

Suitable Grade Level

Grades 11-12