Question

The area of a square is $5.29c{{m}^{2}}$. The area of $7$ such squares taking into account the significant figures will be?
$\begin{align}
  & A.37c{{m}^{2}} \\
 & B.37.0c{{m}^{2}} \\
 & C.37.03c{{m}^{2}} \\
 & D.37.030c{{m}^{2}} \\
\end{align}$

Answer 1

Hint: First of all find out the area of the seven squares using the mathematical operations. The area of one square which is multiplied by seven will be the answer for the total area. We can see that the area of one square is having three significant figures. Therefore, the final answer will also have three significant figures in total. This may help you in solving this question.

Complete answer:
First of all let us mention what all are given in the question. The area of square is mentioned as,
$a=5.29c{{m}^{2}}$
It has been mentioned that there is a total of $7$ squares of the same area. Therefore the total area will be the area of one square which is multiplied by seven. Hence we can write that,
$A=7\times a$
Substituting the value in it,
$A=7\times 5.29=37.03c{{m}^{2}}$
Here the actual answer is obtained as $37.03c{{m}^{2}}$. This is having a total of four significant figures. But when we check the area of each square they are having only three significant figures in it. Therefore the final answer should also be having three significant numbers.
Hence we can write that,
$A=37.03c{{m}^{2}}=37.0c{{m}^{2}}$
The zero after the decimal point can be considered as a significant figure.

So, the correct answer is “Option B”.

Note:
There are some rules for significant figures. All the non-zero numbers in a value are found to be significant. The zeros between two non-zero digits will be significant. Leading zeros are not considered as significant generally. And also trailing zeros to the right of the decimal are found to be significant.