Step 1 :The problem provides us with the formula for Amy's height above the ground after a certain time, which is given by \(H=a \cos (b t)+c\).
Step 2 :We are given the values of \(a=-35\) meters, \(b=0.82\) radians per second, \(t=7\) seconds, and \(c=47\) meters.
Step 3 :We substitute these values into the formula to find the height: \(H=-35 \cos (0.82 \times 7)+47\).
Step 4 :After calculating, we find that \(H=17.03766718569608\) meters.
Step 5 :Rounding this to the nearest hundredth, we get \(H=17.04\) meters.
Step 6 :Final Answer: The height of Amy above the ground at time \(t=7\) seconds is \(\boxed{17.04}\) meters.