Disks of polycarbonate plastic from a supplier are analyzed for scratch and shock resistance. The results from

Question:

Disks of polycarbonate plastic from a supplier are analyzed for scratch and shock resistance. The results from 100 disks are summarized as follows:
Shock resistance
High Low
Scratch high 70 9
Resistance low 16 5
Let A denote the event that a disk has high shock resistance, and let B denote the event that a disk has high scratch resistance. Are events A and B independent?