Final answer:
The error rate of the pocket penetrometer is between 20% and 50%, according to the range given in the question, which is the highest usual error option provided.
Step-by-step explanation:
The error rate of the pocket penetrometer is between 20% and 50%. This range is determined by utilizing the information provided. For example, when we look at the confidence interval (CI) given as (0.18, 0.22), it is indicated that the maximum error bound is ± 3 percent. This suggests that the reported percentages such as the crime rate estimation between 18 percent and 22 percent have a maximum error of 3 percent. Additionally, the principle that increasing the sample size can lower the sampling error reaffirms the tendency that a broader set of data can result in a lower margin of error, which is related but not directly tied to the specific question about the penetrometer's error rate.
In the context of various percentages provided, the closest range that would be appropriate as an answer, without additional specific information about the penetrometer's accuracy, would be Option 3: 50% based on standard options given. It's worth noting that a 20% to 50% error rate is extremely high for any measurement tool, indicating it would be of limited reliability for precise work.