there are 60 minutes marks on a clock
360/60 = 6
6 degree between every minute
From 1:25 to 1:50 there are 25 minutes
25 x 6 = for a total of 150 degrees
150*pi/180 = 5pi/6 radians. ( 2.61799 radians)
Total distance the tip of minute hand has traveled in this time = 2pi*(4 in) * (5pi/6)/(2pi) = 10pi/3 inches (10.47 inches)