You dilute a stock solution containing 25 x 107 cells ml by

You dilute a stock solution containing 2.5 x 107 cells/ ml by a factor of 105 then plate 100 l of the diluted cells onto a YPD plate.

How many colonies do you expect to grow on the plate?

Solution

Number of colonies on YPD plate= Number of cells in stock solution x dilution factor/(volume of culture plate)= 2.5 x 10⁷ cells/ ml x 10⁵/0.1 ml=25 colonies.

You will have 25 colonies on the YPD plate on incubation.