Question 141130
Suppose the record shown played for 16.5 minutes on one side and the average of the radii of the grooves on the record was 3 and 3/4 inches. there are 33 1/3 revolutions per minute. Write an expression involving units that represents how many inches the needle passed through the grooves while the record was being played. then evaluate the expression.
:
This involves finding the average circumference, from the average radius (3.75") 
Multiply this by the no. of minutes played at 33 1/3 rpm
:
D = 2*pi*r * time * record speed (rpm)
:
D = 2*pi*3.75 * 16.5 * 33.33
:
D = 25.562 * 16.5 * 33.33
:
D = 12,958 inches