Question

From a lot of 10 items containing 3 defectives, a sample of 4 items is drawn at random without replacement. The expected number of good items is

• A. $3$
• B. $2.8$
• C. $1.2$
• D. $1.8$

Answer 1

The correct option is B $2.8$

Probability of good items = $7/10$
Total number of items drawn =$4$
Expected number of good items = $4\ast 7/10=2.8$