help with these 2 questions please

Assignment Booklet 3A N Module 3 4. Mark observes a specimen under the medium-power objective lens of a microscope and estimated that it takes up two-thirds of the field of view. If the medium-power field diameter is 1.2 mm, what is the length of the specimen in micrometres? A. 0.4 um B. 1.2 um C. 800 um D. 1200 um 5. The coarse adjustment knob on a microscope should never be used with the A. eyepiece B. low-power lens C. medium-power lens D. high-power lens 6. A microscope has a low-power magnification of 200x and a high-power magnification of 1600x. If the low-power field diameter is 1.2 mm, calculate the high-power field diameter in micrometres (um). Show your work