Fluffy's weight is closest to 9 pounds.
To show this, we will make Fluffy's weight into a decimal, that way it is easier to compare all of the weights. To do so, divide the numerator (3) by the denominator (4). This means Fluffy's weight is 8.75 pounds.
Least to greatest by weight:
Tiger: 8 pounds
Bob: 8.25 pounds
Miss Kitty: 8.5 pounds
Fluffy: 8.75 pounds
Thus meaning Fluffy weighs the most. I hope this helps!