Question

Fred read a book about bread making and learned that in many breads, yeast cells are responsible for causing the dough to rise. He read that yeast cells increase in number by about 59% each hour. If a ball of dough initially contains about 100 billion yeast cells, you can use a function to approximate the number of yeast cells in the dough, in billions, x hours into the rising process.
Is the function linear or exponential? make an equation that best represents the function.

Answer 1

The growth is exponential (the yeast multiplies by a constant factor each hour).

Let N(x) be the number of yeast cells in billions after x hours. Then
N(x) = 100(1.59)^x, x ≥ 0.

(Here 1.59 = 1 + 0.59, since the population increases by 59% each hour.)