Question

During the assembly of a certain piece of exercise equipment, 3 welds are required during different phases of the assembly process. It is assumed that the welds are performed independently of one another. Due to variation in the materials used and in technique, only 97% of all welds are performed satisfactorily, with the remaining 3% being classified as defective. What percentage of all pieces of this type of equipment will have at least one defective weld

Answer 1

Answer:

99.9973 %

Step-by-step explanation:

This is a binomial probability distribution.

Since the probability of satisfactory welds = 97% = 0.97 and the probability of defective welds = 3% = 0.03.

Since there are 3 welds and we require at least one being defective, our binomial probability is

P(x ≥ 1) = 1 - P(x ≤ 0) = 1 - P(0) = 1 - ³C₀(0.03)³(0.97)⁰ = 1 - 1 × ‭0.000027‬ × 1 = 1 - 0.000027 = 0.99997‬3 × 100% = 99.9973%