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 resistance |
high |
68 |
13 |
| low |
15 |
4
|
a) If a disk is selected at random, what is the probability that its scratch resistance is high and its shock resistance is high? Round your answer to two decimal places (e.g. 98.76).
b) If a disk is selected at random, what is the probability that its scratch resistance is high or its shock resistance is high? Round your answer to two decimal places (e.g. 98.76).