At midnight the water at a particular beach is at high tide. at the same time a gauge at the end of a pier reads 10 feet. low tide is reached at 6 am when the gauge reads 4ft. answer the questions that follow using this scenario. determine the amplitude. a.) 6 feet b.) -3 feet c.) 3 feet d.) 12 feet only answer if you're smart, this question is worth 10 points : ) you

The motion of tides can be roughly modelled using a sine function, i.e. asin(bx)+c

The amplitude of a sine graph is half the distance from the maximum to the minimum, so in this case it is (10-4)/2 = 3
Amplitudes are the equivalent of absolute values (i.e. think of it as the distance to a number on a number line, disregarding which way you're going), and therefore can only be positive. Therefore the amplitude of this is c) 3 feet, since at mid tide the buoy will be at 7 feet, climbing to 10 feet and falling to 4 feet, cyclically.