A. The answer is 2 1/2 gallons of water.
A freshwater fish is healthiest when there is at least one gallon of water for every inch of its body length: 1 gallon for 1 inch
Roshel wants to put a goldfish that is about 2 1/2 inches long in her tank. So, she needs x gallons of water. x gallons for 2 1/2 inches
Make a proportion:
1 gallon : 1 inch = x : 2 1/2 inches
x = 1 gallon * 2 1/2 inches : 1 inch
x = 2 1/2 gallons.
B. The answer is 245 in³.
Roshels tank is 7 inches long, 5 inches wide, and 7 inches high.
The volume of a rectangle is:
V = length * width * height
V = 7 in * 5 in * 7 in
V = 245 in³
C. The answer is her tank is not large enough for the fish.
Rachel needs 2 1/2 gallons for the fish and has 245 in³ big tank.
Express 2 1/2 gallons in cubic inches if the volume of 1 gallon of water is about 231 cubic inches:
2 1/2 gallons : x = 1 gallon : 231 in³
5/2 gallons : x = 1 gallon : 231 in³
x = 5/2 gallons * 231 in³ : 1 gallon
x = 577 1/2 in³
Since 577 1/2 in³ is bigger than the volume of the tank 245 in³, then her tank is not large enough for the fish.