Final answer:
The size of the cells in microns cannot be determined without a scale reference or known magnification details; comparisons to known cell sizes or calibration with a known size is required.
Step-by-step explanation:
To determine the size of the cells, one would need either a scale marker on the micrograph or must calibrate the microscope with a known size. Once that is established, you can use the microscope's eyepiece with a reticle or compare the cells to a known size, such as how many of the cells fit across the width of a human hair, which is typically about 70 µm wide.
Understanding that the typical human red blood cell is approximately 8 µm in diameter and a bacterial cell like Bacillus cereus is approximately 4 µm long, one could estimate the size of an unknown cell if it were compared to these known reference sizes under the same magnification. Remember, microscopes can magnify up to 400 times in a standard high school lab setting, affecting perceived sizes on micrographs.