Aparticular element found in nature exists as two stable isotopes. 60.4% of the element has a mass of 68.9257amu, the rest of the element is found with a mass of 70.9249 amu. calculate the average atomic mass of the element.

Mass           %abundance        # of atoms (pick 1000 sample)
68.9257         60.4%                  604
70.9249         39.6%                  396
*39.6* ( i got this by subtracting 100 as most percentage is out of 100)
*# of atoms* ( i just moved it one decimal place, then i am going to make the sample out of 1000, to get the decimal place)

Formula= total mass/ total #atoms

x= (68.9257u* 604) + (70. 9249*396)/ 1000
x- 69717. 3832/ 1000
x= 69.717amu or 69.72 amu 

if you look on the periodic table the closet element with that mass is gallium ( amu is 69.72)

Mass is the amount of matter in an object.  weight is the measurement of the pull of gravity on an object.  say for example, you travel to the moon which has a different gravitational field compared to the gravitational field of earth. (gravitational fields: earth = 1, moon = 0.165)  now when you are on the moon, the pull of gravity on you is different than on the earth. and as weight is the measurement of the pull of gravity on an object, that means yes, your weight can and will change on the moon.  however, on the moon, on earth or even on jupiter, the amount of mass inside of you remains the same. meaning your physical mass remains constant.  in conclusion it is possible for your weight to change as your mass remains constant. 

Is there a picture or answer choices?