Explanation:
the volume of a cylinder is in general
base area × height = pi×r²×height
with r being the radius (= half of the diameter) of the circle.
so, now we only need a calculator and type the numbers in.
4.
pi×(6/2)²×5 = pi×3²×5 =pi×9×5 = 45pi = 141.3716694... m³
5.
pi×7²×15 = pi×49×15 = 735pi = 2,309.0706... ft³
6.
pi×(8/2)²×8 = pi×4²×8 = pi×16×8 = 128pi =
= 402.1238597... mm³
7.
pi×(10/2)²×11 = pi×5²×11 = pi×25×11 = 275pi =
= 863.9379797... cm³
8.
pi×7²×13 = pi×49×13 = 637pi = 2,001.19452... in³
9.
pi×3²×7 = pi×9×7 = 63pi = 197.9203372... m³
10.
the "width" of 6 cm just means the diameter is 6 cm.
so,
pi×(6/2)²×15 = pi×3²×15 = pi×9×15 = 135pi =
= 424.1150082... cm³