The formula of the volume for a cylinder is pir^2h. Given the diameter of 1 inch and height/length of 2.5 inches, the volume is calculated by:
V = pi(0.5^2)2.5 = 1.9625 in^3
the cork density is 0.26 g/mL, since the units of the volume is in^3, convert to cm^3 or mL:
1.9625 in^3 (2.54cm/1in)^3 = 32.16 cm^3
So, the mass of the cylindrical cork is 0.26 g/mL 32.16 cm^3 = 8.36 g