Accurate to one tenth, accurate to 110, that is, reserved to1bit after the decimal point.

1* 30%+2 * 60%+3 *10% has been weighted because of its percentage. If you divide by (1+2+3), it is nothing.

Besides, (1+2+3) is not a total. If it is your form, it should be:

( 1*30%+2*60%+3* 10%)/(30%+60%+ 10%)= 1*30%+2*60%+3* 10%