Answer:
It is not possible to determine the actual size of the cell without a scale viewed under that same magnification. As a scale for microscopy, a ruler should be placed under the microscope and the microscope lens units should be compared with that of the ruler to obtain the scale. (1cm on the ruler= ? microscope lens units). The microscope lens units can then be used to measure the length of the cell and the actual length of the cell can be obtained under that magnification.