To what decimal place should each answer be rounded? How many significant figures does the rounded answer have?

(a) 101 cm-99.1 cm=1.9 cm (unrounded) After rounding, the answer should be reported to the (ones place / tenths place / hundredths place) and thus has (1 significant figure / 2 significant figure / 3 significant figure) (b) 0.5 atm + 9.8 atm = 10.3 atm (unrounded) After rounding, the number should be reported to the (ones place / tenths place / hundredths place) and thus has (1 significant figure / 2 significant figure / 3 significant figure).

These are two questions and two answers

Answer:

a) After rounding, the answer should be reported to the (ones place) and thus has (1 significant figure)

b) After rounding, the number should be reported to the (tenths place) and thus has (3 significant figure).

Explanation:

(a) 101 cm-99.1 cm = 1.9 cm (unrounded)

When adding or subtracting quantities, the final result must be rounded to the least number of places in the decimal part of any of the quantities in the operation.

The number 101 has zero decimals while the number 99.1 has 1 decimal place, so the least number of decimals between those two quantities is 0, so the final result must contain no decimals.

In this case, 1.9 cm, which has two significant figures, must be reported with no decimals, so it must be rounded to one signficant figure, i. e. 2 cm.

After rounding, the answer should be reported to the (ones place) and thus has (1 significant figure)

(b) 0.5 atm + 9.8 atm = 10.3 atm (unrounded)

Here you are adding two quantities, so use the same rule: round to the least number of places in the decimal part of any of the quantities in the operation.

Both 0.5 atm and 9.8 atm have one decimal (tenths place), so the answer must contain one decimal too, meaning that it stands as 10.3 atm, which has three significant figures.

So, the answer is:

After rounding, the number should be reported to the (tenths place) and thus has (3 significant figure).