Answer to Question #214273 in Statistics and Probability for ratie

Question

In a certain manufacturing process, 10% of the articles manufactured are defective. Let  be the number of defective articles. If four articles are selected at random, what is the expected value of ?

Answer 1

$p = 10 \; \% = 0.1 \\ n=4$

The expected value of defective articles $np= 4 \times 0.1 = 0.4 ≈ 0$