Rithick went to the shop to buy cardboard. The shop has different sizes of cardboard available, as shown below.
| Size (in inch) (\(x\)) | \(5\) | \(10\) | \(15\) | \(20\) |
| Cost of the cardboard \(₹\) (\(y\)) | \(25\) | \(50\) | \(75\) | \(100\) |
(i) Find the type of variation.
(ii) Graph the data and find the cost of the cardboard if its size is \(12 \ in\)