Calculating drawing size:actual size?

You viewed a cell under medium power (10x objective) and, using the calibrated ocular micrometer, you determined that it was 40 micrometers in length. You then drew a diagram of the cell. The cell, in your drawing, was 8 cm in length. What is the scale of this diagram? Provide your answer in ratio format, as drawing size:actual size, where drawing size is rounded to the appropriate number of sig figs and actual size is equal to 1 (ie. 1000:1). Do not include spaces in your answer.