Question

Three samples were weighed using three different balances. all measurements are as accurate as the precision below indicates. the weights are 1.21 kg, 546 mg, and 23.14 g. using significant figures, the total mass should be reported as

Answer 1

In adding measurements, we should remember that the units of the values to be added should be homogeneous which means all addends should have the same units. For this case, we must convert all the masses to units grams. The total mass of the of the all the masses weighed is:

1.21 kg ( 1000 g / 1 kg ) + 546 mg ( 1 g / 1000 mg ) + 23.14 g = 1233.686 grams
To correctly report this, it should be written in scientific notation which would be 1.23 x 10^3 g. In adding, the least number of significant figures should be followed. In this case, it is 3 significant figures.