Question

side of a cube is 7.20 cm surface area of cube with correct significant figure

Answer 1

311 cm²

Answer 2

The side of the cube is given as $l = 7.20 \, \text{cm}$.
The number of significant figures in the given side length is three (7, 2, and the trailing zero after the decimal point).

The formula for the surface area ($SA$) of a cube is: $SA = 6 \times l^2$

Substitute the value of $l$: $SA = 6 \times (7.20 \, \text{cm})^2$ $SA = 6 \times (7.20 \times 7.20) \, \text{cm}^2$ $SA = 6 \times 51.84 \, \text{cm}^2$ $SA = 311.04 \, \text{cm}^2$

According to the rules of significant figures for multiplication, the result should have the same number of significant figures as the measurement with the fewest significant figures.
The side length $7.20 \, \text{cm}$ has three significant figures. The number 6 is an exact number and does not limit the significant figures.
Therefore, the surface area must be rounded to three significant figures.

The calculated value is $311.04 \, \text{cm}^2$.
To round this to three significant figures, we look at the fourth digit (which is 0). Since 0 is less than 5, we do not round up the third significant figure.

So, the surface area with the correct significant figures is $311 \, \text{cm}^2$.