All of the questions can be answered with the following equation....you are given all of the variables except one.....plug in the given numbers and solve for the unknown:
In each question , you are given all but one of the variables......plug in the values and solve for the unknown variable....
Example: 1 M1 = 447 kg M2 =285 kg r = 27 m and G is given above....plug in all of the values and solve for Fgrav
WATCH out on the last question distance given is KILOmeters....convert to meters to use in the equation !!!