Final answer:
Joey has encountered problems with the objective lens, course adjustment knob, and eyepiece lens of the compound microscope.
Step-by-step explanation:
Joey has encountered several problems with the compound microscope as he prepares to work on his plant cell experiment. First, one of the objective lenses is missing. The objective lens is responsible for magnifying the object and creating a real image. Without it, Joey won't be able to properly view the plant cell.
Second, the course adjustment knob is not working. This knob is used to make large-scale focusing adjustments. Without it, Joey won't be able to quickly and accurately focus on the plant cell.
Lastly, the eyepiece lens is broken. The eyepiece lens further magnifies the real image created by the objective lens. Without a functioning eyepiece lens, Joey won't be able to properly see the magnified image of the plant cell.