Q 2.11: 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.
Length, l = 4.234 m ; Breadth, b = 1.005 m; Height, h = 2.01 cm = 0.0201 m
The length has 4 significant figures
The breadth has 4 significant figures
The height has 3 significant figures (Since the number is less than 1, hence zeroes after decimal before the first non-zero integer is insignificant)
Surface area of a cuboid = 2(l x b + b x h + h x l)
= (Note: For addition/subtraction, the number of places after the decimal point in the answer is less than or equal to the number of decimal places in every term in the sum; i.e decided by the numbers after the decimal.)
Volume = l x b x h
= = ( 3 significant digits)
(Note: For Multiplication The LEAST number of significant digits in any number determines the number of significant figures in the answer; i.e decided by the number of significant digits)
The area has three significant values 2, 7 and 8.
The volume has three significant values 5, 5 and 8.