Final answer:
The original question lacks specific context, making it impossible to determine the average fish length without additional information. However, the examples provided illustrate the application of statistics in contexts such as measuring fish mass and evaluating fish counts in aquariums.
Step-by-step explanation:
The student's question regarding the "average length of fish" seems to lack the necessary context to provide a direct answer. It is mentioned that lengths are normally distributed, which is a statistical term describing how data is dispersed around a mean (average) value. The options given for the average length include measurements in millimeters (mm) and grams (g), which are units for length and mass respectively.
However, if we consider a theoretical scenario where fish lengths are normally distributed with a known average, we could refer to that value as the mean of that normal distribution.
Regarding the additional context provided, it relates to different settings in which statistical analysis is applied, such as a spring scale's extension due to the fish's mass (Physics), the standard deviation of fish counts in aquariums (Biology), and the normal approximation for sample sizes (Statistics). These settings illustrate various applications of mathematical concepts in real-world scenarios.