Question

Nine days ago the area covered by the piece of bread was $3inc{h}^2$. Total, the mould covers $9inc{h}^2$. What is the rate of change in moulds area?

Answer 1

Step 1: Given data

Time = $9$ days

Area covered by the bread = $3inc{h}^2$

Mould area = $9inc{h}^2$

Step 2: Solution

To calculate the change in area:

Change in area = Final area − initial area

Change in area = $\left(9-3\right)inc{h}^2$

Change in area = $6inc{h}^2$

But according to the question it has mentioned that we have to calculate the rate of change in mould’s area.

Thus, the rate of change of mould's area = (change in the area) / (time taken)

Hence, the rate of change in mould’s area = $\frac{\left(9-3\right)}{9}=\frac{2}{3}inc{h}^2$
Therefore, the rate of change in the area of mold is $\frac{2}{3}inc{h}^2$ per day.