Answer:
51.7mm
Step-by-step explanation:
#Find the minimum bound of the back/front thickness:
-Given that it's rounded to one decimal point, the margin or error will be:

We subtract this ME from the front thickness to get the minimum thickness:

#Find the minimum bound of the pages:
-Given that it's rounded to one decimal point, the margin or error will be:

We subtract this ME from the page thickness to get the minimum thickness:

The minimum book thickness is thus calculated as:

Hence, the minimum thickness of the book is 51.7 mm