Answer: 123.5 μm
If it served you, give me 5 stars please, thank you!
____________________________________________________
(a) Total power of magnification 100x because ocular lens is 10x magnification maultiplied by 10x objective lens.
(b) Widht of the onion cell can be calculated as follows:
If the number of units observed for an onion cell through ocular micrometer (10x) under microscope is 'A'.
Then, the widht of the cell will become = A X 9.5 (Calibration factor of ocular unit and total power fo magnification is 100x)
So, for example if the observation through ocular micrometer is 13, then the widht of the onion cell will be = 13 X 9.5 = 123.5 μm