
### Instruction: help me answer this question Calculate the standard deviation and mean diameter of the circles., think step by step
### Assistant: To calculate the mean and standard deviation, the reader must first convert the given classes to a continuous form, then calculate the midpoints, Yi, Yi2, fiyi, and fiyi2, and finally use those values to find the mean and standard deviation using the formulae provided in the question. , The answer is The mean diameter of the circles is 43.5 mm and the standard deviation is 5.553 mm.
