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:
[tex]\begin{gathered} 1.72,17.2,172,0.17 \\ \end{gathered}[/tex]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:
[tex]3.045,7.0011,0.048,0.10[/tex](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:
[tex]101-83.4=17.6\text{ (3 significant figures)}[/tex]Option A is correct
Option B:
[tex]\begin{gathered} 121\div1.75=69.14285714 \\ \therefore\text{ not 3 significant figures} \end{gathered}[/tex]Option B is wrong
Option C:
[tex]\begin{gathered} 7.23+12.6=19.83\text{ (There are 4 digits)} \\ \therefore\text{ not 3 significant figures} \end{gathered}[/tex]Option C is wrong
Option D:
[tex]\begin{gathered} 17\times1.5=25.5\text{ (There are 3 digits)} \\ \\ \therefore\text{This is 3 significant figures} \end{gathered}[/tex]Option D is correct
Therefore, the final answers are: Option A and Option D