A sample of 60 ball bearings are tested for roundness. Of the ball bearings tested, 15 of them are round enough to pass inspection. The probability of a ball bearing being round enough to pass inspection in the population is 0.25. 1. What is the sample proportion of the ball bearings? A: 0.15 B: 0.25 C: 0.50 D: 0.60 2. What is the sample standard deviation of the ball bearings sample? A: 0.0003 B: 0.06 C: 0.19 D: 0.25 3. What is the probability that less than 30% of the ball bearings are round enough to pass inspection? A: 0.19 B: 0.25 C: 0.30 D:
0.81