Pythagorean's theorem says the hypotenuse of a triangle is A^2+B^2=C^2 in this case I'll put the L,W, and D so it's easy to understand. L^2+W^2=D^2 is the exact same formula as above and is how we will solve this. (30^2)+(10^2)=1000 then we take the square root since 1000=D^2, and we get 36.62 as D.
12 inches go into one foot, so we can calculate the volume of the tank in inches to make the calculations that follow easier. Therefore, to calculate the volume of the tank, we use length x breadth x height = 4 x 2 x 2 = 16 square feet x 12 for square inches = 192 square inches.
Every 12 square inches Joseph can fit a one inch fish. The fish that he has are 3 inches long, therefore he can only fit one fish every 36 square inches.
That means that if we take the total volume of the tank and divide it by the space that a 3 inch fish will take up, we are left with 192/36 = 5.3 fish.
You cannot have a third of a fish, so we round off to the nearest whole number, and we determine that Joseph can put 5 fish in his new aquarium.
The answer would be 168 minutes.