Status: Waiting for your answer. Formula: Given: There are 13 cells of a treponema pallidum colony.This colony has a double rate of 1.5 days within an optimum medium. Find: Use the formula above to calculate the time it would take for the given colony to grow to 900000 cells within an optimum medium. Calculate the solution for 't' to the nearest tenth using logarithms. Solution: t = days