A good way to tell if a fruit cake is cooked is to see if the fruit cake is moist and the fruit cake is done when a meat thermometer put in the center of the fruit cakes reads a minimum of 195 F.
If the meat thermometer says 195 F in the center of the fruit cake then the fruit cake is done and ready to serve.
A properly cooked fruit cake should be moist and not dry.
If you stick a fork in the cake and it comes out with some cake batter then the cake is done done and should be cooked longer.
Most cakes including fruit cakes take around 30 to 35 minutes to fully cook or bake depending on the size of the cake.
The time it takes to bake a 9 inch round cake is between 30 to 35 minutes at 350 F degrees.
Preheat the oven to 350 F degrees and then place the cake into the oven on the middle rack and then set a timer for 35 minutes.
Check the round cake after 30 minutes to see if it has fully baked and if not allow the cake to cook or bake another 5 minutes.
If you put the cake on the very bottom rack that is too close to the heating element or heat then the cake could crack because it's getting dried out and getting too much heat.
So make sure to put the cake on the middle rack when baking the cake.