Answer:
Step-by-step explanation:
Total number of laptops, N = 20
Defective laptops, n = 3
School purchase 2 laptops
Case 1:
Both laptops are non defective
Probability to choose 2 laptops which are non defective
Number of non defective laptops = 20 - 3 = 17
Total number of laptops = 20
Probability, P = 17/20 = 0.85
Case 2:
One laptop is defective
Probability to chose 1 defective and one non defective laptop
P' = 3/20 x 17/19 = 0.134
Case 3:
Both laptops are defective
Choosing of 2 laptops out of 3 = 3 C 2 = 3
choosing of 2 laptops out of 20 = 20 C 2 = 190
Probability of choosing two defective laptops = 3 / 190 = 0.0158
P'' =
