Final answer:
First, we need to calculate the probability of selecting a defective item, which is given as 100 defective items out of 500 total items, or a probability of 0.2.
Next, we can use the binomial probability formula to calculate P(X = 5) = (20 choose 5) * (0.2)^5 * (0.8)^15 = 0.026.
Step-by-step explanation:
To calculate the probability of selecting exactly 5 defective items out of a total of 20 items, we can use the binomial distribution formula.
First, we need to calculate the probability of selecting a defective item, which is given as 100 defective items out of 500 total items, or a probability of :
100/500
= 0.2.
Next, we can use the binomial probability formula, which is P(X = k) = (n choose k) * p^k * (1-p)^(n-k), where n is the total number of items selected, k is the number of defective items selected, and p is the probability of selecting a defective item.
P(X = 5) = (20 choose 5) * (0.2)^5 * (0.8)^(20-5)
Using factorials, (20 choose 5)
= 20! / (5! * (20-5)!)
= 15504
Substituting the values, P(X = 5)
= 15504 * (0.2)^5 * (0.8)^15
= 0.026.