3. PolyA+ RNA from hormone-stimulated chicken ovaduct was analyzed by RNA dot blotting using a cloned, 32P-labeled ovalbumin cDNA probe. The intensity of hybridization of the probe to polyA+ RNA from 105 cells equaled the intensity of hybridization of the probe to 20 ng of a 12 kb single-stranded M13 clone containing a complete ovalbumin cDNA insert. Calculate the number of ovalbumin mRNA molecules per hormone-stimulated cell. (Notes: polyA+ RNA is the total mRNA in a cell; cDNA is a DNA copy of a specific mRNA.)