834 cubic centimeters.
First, determine the cross section of the pipe. And that's simply the area of the outer diameter minus the area of the inner diameter. So calculate the inner and outer radius of the pipe
IR = 2.6 / 2 = 1.3
OR = 2.8 / 2 = 1.4
Now the inner and outer areas.
IA = pi * IR^2 = 3.14159265 * 1.3^2 = 5.309292
OA = pi * OR^2 = 3.14159265 * 1.4^2 = 6.157522
Cross section area is simply the outer area minus the inner area. So
CS = 6.157522 - 5.309292 = 0.84823
Now figure out the volume in cubic inches by multiplying the cross section by the length. Be sure to include the 12 to convert from feet to inches.
V = 0.84823 * 5 * 12 = 50.8938
Now to convert from cubic inches to cubic centimeters. Since there is 2.54 centimeters per inch, just multiple by 2.54^3 to convert.
50.8938 * 2.54^3 = 50.8938 * 16.38706 = 834
