Answer:
Books should be kept in second box.
Explanation:
If the sum of all the weight of all books is between 4 and 6 pounds then it should be kept in first box
If the sum of all the weight of all books is between 5 and 7 pounds then it should be kept in second box
If the sum of all the weight of all books is between 8 and 9 pounds then it should be kept in first box .
Here sum of the weighs of all the books = 3.1lb+2.4lb +0.75lb
= 6.25 lb
Here we can see that 6.25 lb lies between 5 and 7 which is the weigh limit
for the second box
therefore we can keep the books in second box.