Question Details

The length, breadth and thickness of a rectangular sheet of metal are 4.234 m, 1.005 m and 2.01 cm, respectively. Give the area and volume of the sheet to correct significant figures.

Options

A

8.27 m² and 0.0844 m³

B

9.72 m² and 0.0855 m³

C

7.82 m² and 0.0865 m³

D

8.72 m² and 0.0855 m³

Correct Answer :

8.72 m² and 0.0855 m³

Solution :

The correct option is 8.72 m² and 0.0855 m³.

Let's solve the problem step-by-step to determine the area and volume of the metal sheet with the correct number of significant figures.

1. Identify the given dimensions:
Length, l=4.234 m (4 significant figures)
Breadth, b=1.005 m (4 significant figures)
Thickness, t=2.01 cm=2.01×10-2 m=0.0201 m (3 significant figures)

2. Calculate the Total Surface Area:
The total surface area A of a rectangular sheet is given by the formula:
A=2(lb+bt+tl)

Let's calculate the individual term products:
lb=4.234×1.005=4.25517 m2
bt=1.005×0.0201=0.0202005 m2
tl=0.0201×4.234=0.0851034 m2

Summing these values:
lb+bt+tl=4.25517+0.0202005+0.0851034=4.3604739 m2

Multiplying by 2:
A=2×4.3604739=8.7209478 m2

According to the rules of significant figures, the final result of addition/multiplication should match the least precise measurement. The thickness t=2.01 cm has the least number of significant figures (3 significant figures). Therefore, the total area should be rounded off to 3 significant figures:
A8.72 m2

3. Calculate the Volume:
The volume V of the rectangular sheet is given by:
V=l×b×t
V=4.234×1.005×0.0201=0.085528917 m3

Since the minimum number of significant figures in the given values is 3 (from the thickness, 2.01 cm), we round the volume to 3 significant figures:
V0.0855 m3

Thus, the area and volume of the sheet to the correct significant figures are 8.72 m² and 0.0855 m³, respectively.

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