Help with a biology question?

How long does mitosis take in root tip cells? if it takes a whole day, and any individual cell reproduces every 11 days, then the fraction of time it spends in mitosis is 1/11, so for fifty cells, at any given time, 50/11 or about 5 cells will be in mitosis. figure out how much of one cell's time is spent in mitosis, and multiply by the total number of cells