The volume of a cylinder is just the area of one of its end (a circle) multiplied by the height. With the area of a circle being given by :
than you volume with by Area by height. ie
the radius of a circle is just half of its diameter.
diameter = 18cm therefore radius = 1/2 * 18 = 9cm
your height is given as 2.5cm
Therefore you work your volume out as below
Accuracy to 1/10th just means to 1 decimal place ie because answer is 636.1725124.... accurate to 1/10th or 1 decimal place will be to round up giving answer as 636.2