Question

Which of the following expressions will produce an answer with threesignificant figures? Check all that apply.

Answer 1

The answers are: Option A and Option D

The question asks us to check which of the options will result in an answer that is in 3 significant figures.

Examples of 3 Significant figures are shown below:

`\begin{gathered} 1.72,17.2,172,0.17 \\ \end{gathered}`

As long as there are 3 digits in the number, then the number is in 3 significant figures. However, there is an exception to this rule: Any zero (0) that comes after a decimal point is never counted as a significant number.

Therefore, we can write other examples of numbers in 3 significant figures:

`3.045,7.0011,0.048,0.10`

(Note:

1. Any zero (0) before the decimal point MUST be counted as a significant number.

2. Any zero (0) after the decimal point but which comes after another number, like in the case of 0.10, MUST be counted as a significant number.

3. Any zero (0) that comes after a zero (0) after a decimal point is also NOT counted.

With this information, we can proceed to solve the question.

Option A:

`101-83.4=17.6\text{ (3 significant figures)}`

Option A is correct

Option B:

`\begin{gathered} 121/1.75=69.14285714 \\ \therefore\text{ not 3 significant figures} \end{gathered}`

Option B is wrong

Option C:

`\begin{gathered} 7.23+12.6=19.83\text{ (There are 4 digits)} \\ \therefore\text{ not 3 significant figures} \end{gathered}`

Option C is wrong

Option D:

`\begin{gathered} 17*1.5=25.5\text{ (There are 3 digits)} \\ \\ \therefore\text{This is 3 significant figures} \end{gathered}`

Option D is correct

Therefore, the final answers are: Option A and Option D