Answer:
It is 437.5
Explanation:
The median refers to the value in the middle of a set of number or observation. If the set is uneven, the value is one of the numbers, if the number of observation is even, then is the average between the two numbers in the middle.
In this set, we know that on upper shelf the maximum number is 400 pages. So all the other books contain less pages than or equal amount of pages to the book with 400 pages.
On the lower shelf the books have at least 475 pages.
So we can express our sets in this way
Upper shelf (x ; 400)
Lower shelf (475 ; Y)
The median of the number of pages between this 2 shelves is the number between 400 and 475.
So it is 437.5