Resolution

This is an example of the difference between resolutions. A larger image can be distorted if the PPI is lower than the 2 inch image size. However if the image is smaller the PPI will remain the same.

I then found this image from Google where we had to work out how the original dimensions came down to millimetres & centimetres. 

500x375
500/72 = 6.94
375/72 = 5.20
6.94(7) x 5.20(5) = 36.088

Divided by 300
500/300 = 1.6
375/300 = 1.25

Millimetres into Centimetres 
1.6 x 2.54 = 4.064mmx10 = 40cm
1.25 x 2.54 = 3.175mmx10 = 31.75cm

40 cm
31.75 cm