The size of actual bed is 75 inches
Explanation:
Scale refers to the ratio of the original dimension to the dimension on paper (miniaturised dimension). Since it is a ratio, it has no dimension.
Scale= original dimension/miniaturised dimension
Given that scale is 1:25
It means that every 1 inch on paper would correspond to 25 inches in reality.
The length of the model bed= 3 inches
Hence, the length of the original bed is 25*3 = 75 inches
∴ Length of the actual bed of the student is 75 inches.