Equal numbers of fibroblasts and endothelial cells are present initially in a culture.
a. If endothelial cells double every 40 hours and fibroblasts double every 20 hours, draw a graph showing the percentage of cells in the culture that are fibroblasts as a function of time.
b. What is the time required for the culture to contain 90% fibroblasts? Write an equation that describes this situation and, when solved for time, will provide the correct answer.