Answer:
105 minutes
Step-by-step explanation:
The volume of the terrarium is ...
V = LWH
V = (42 in)(10 in)(9 in) = 3780 in³
The volume of a box is ...
V = (3 in)(3 in)(3 in) = 27 in³
Then the number of boxes it takes to fill the terrarium is ...
(3780 in³)/(27 in³/box) = 140 boxes
The mermaid wants to fill it 3/4 full, so only needs 3/4 this number of boxes. That is 105 boxes. At the rate of 1 per minute, ...
it will take 105 minutes to fill 3/4 of the terrarium
