D 34 is the right answer because 30+30+35+35+40=170 and 170/5=34 and that is your mean
hope i helped you out
The recommended ratio of gallons of water per fully grown goldfish in a tank is 12:1. This means for every goldfish that grows up to 12 inches, there should be 12 gallons of water in the tank.
James is setting up a fish tank and planning to house a breed of goldfish that typically grows to be 12 inches long. Considering the recommendation, there should be 1 gallon of water for every inch of fish length in the tank. Therefore, for a fully grown goldfish of 12 inches, James will require 12 gallons of water per goldfish - this is the recommended ratio of gallons of water per fully grown goldfish in the tank.
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