PRACTICE ANOTH The wave heights h in the open sea depend on the speed v of the wind and the length of time t that the wind has been blowing at that speed. Values of the function h (v, t) are recorded in feet i SK YOUR TEACHER The table below. Wave height as a function of wind speed and duration Duration (hours) V t 5 10 15 20 30 40 50 10 10 2 2 2 2 2 2 2 15 4 4 5 5 5 5 5 Wind 20 5 7 8 8 9 9 9 speed (knots) 30 9 13 16 17 18. 19 19 40 14 21 25 28 31 33 33 50 19 29 36 40 45 48 50 60 24 37 47 54 62 67 69 a) What is the value of f(30, 20)? What is its meaning? According to the table, f(30, 20) which means that if a 30 knot wind has been blowing in the open sea for 20 hours, it will create waves with estimated heights of