Final answer:
The probability of a defect is approximately 0.32 when the standard deviation is 0.1 and the process control is set at plus or minus one standard deviation.
Step-by-step explanation:
To calculate the probability of a defect in this scenario, we need to find the area under the normal distribution curve that falls outside the range of weights that are within plus or minus one standard deviation (0.1 ounces) from the process mean. Since the standard deviation is 0.1 ounces, we can use the empirical rule to estimate the probability of a defect. According to the empirical rule, about 68% of the data falls within one standard deviation of the mean, meaning that the remaining 32% falls outside that range. Since the process control is set at plus or minus one standard deviation, both the weights less and greater than one standard deviation from the mean will be classified as defects. Therefore, the probability of a defect is approximately 0.32.