Answer :
To determine the amplitude we need to see where is the middle line of the function, the middle line passes through the middle value of the y components of the maximum and minimum. Then the middle line passes through;
[tex]\frac{1.25+6.75}{2}=4[/tex]Now, the amplitude is the vertical distance between the maximum and the middle value, then in this case we have:
[tex]6.75-4=2.75[/tex]Therefore the amplitude is 2.75