Answer:
3 3/5 minutes
Explanation:
Let one measure of volume be 5/9 of a tank, or (5/9)(tank).
We're interested in filling the whole tank, which we represent by (1)(tank) or (9/9)(tank.
Write and solve an equation of ratios:
(5/9) (tank) 2 minutes
------------------- = ----------------
(9/9) (tank) x
Solve for x, which represents the number of minutes required to fill the whole tank:
(5/9)(x) = (9/9)(2), or (after simplifying) 5x = 18, or x = 18/5 (3 3/5 minutes)
The whole tank will be filled in 3 3/5 minutes.