Two objects have masses of 1.155 kg and 0.22 kg, respectively. Using the correct number of significant figures, what is the sum of these masses?

Question

1 kg
1.375 kg
1.4kg
1.38kg

Answer 1

To find the sum of the two masses, you first need to add the values:

1.155 kg + 0.22 kg = 1.375 kg.

Now, when rounding based on significant figures, you need to consider the least number of decimal places in the values being added.

• The mass 1.155 kg has three decimal places.
• The mass 0.22 kg has two decimal places.

Since the value with the least decimal places is 0.22 kg (which has two decimal places), you should round the sum to two decimal places:

1.375 kg rounded to two decimal places is 1.38 kg.

Therefore, the sum of the masses, with the correct number of significant figures, is 1.38 kg.