Yeast growth Consider a colony of yeast cells that has the shape of a cylinder. As the number of yeast cells increases, the cross sectional area $A\left(\text {in } m m^{2}\right)$ of the colony increases but the height of the colony remains constant. If the colony starts from a single cell, the number of yeast cells (in millions) is approximated by the linear function $N(A)=C_{s} A,$ where the constant $C_{s}$ is known as the cell-surface coefficient. Use the given information to determine the cell-surface coefficient for each of the following colonies of yeast cells, and find the number of yeast cells in the colony when the cross-sectional area A reaches $150 \mathrm{mm}^{2} .$ (Source: Letters in Applied Microbiology, 594 , 59,2014)
The scientific name of baker's or brewer's yeast (used in making bread, wine, and beer) is Saccharomyces cerevisiae. When the cross-sectional area of a colony of this yeast reaches $100 \mathrm{mm}^{2}$ there are 571 million yeast cells.