Answer:
The actual mass of the book is between 481 . 5 g and 418 . 5 g.
Step-by-step explanation:
The mass of the book on the scale = 450 g
The percentage error in the scale = 7%
So, the actual mass of the book is 450 g ± 7%
Now, 7 % of the mass 450 g = 
⇒ 7% of 450 g = 31.5 g
Now, the Actual mass of the book = 450 g ± 31.5 g
450 g + 31.5 g = 481 . 5 g
450 g - 31.5 g = 418 . 5 g
Hence the actual mass of the book is between 481 . 5 g and 418 . 5 g.