Answer:
Hourly growth rate is 4.24%
Explanation:
The formula or exponential growth is given by:
![y = a*(1+r)^n](https://img.qammunity.org/2021/formulas/mathematics/high-school/fb44yfr8d3ddo3npeqy96jcxitrapbz3hx.png)
Where
y is the instantaneous value of growing culture
a is the initial value of growing culture
r is the 'hourly' growth rate
n is the number of hours passed
As per given values:
y = 1997; a = 1800; n = 2.5
![1997 = 1800*(1+r)^(2.5)](https://img.qammunity.org/2021/formulas/mathematics/high-school/c45rfclv6gxwmdutl2sywa7i1wc0y7cmf3.png)
![1.10944=(1+r)^(2.5)](https://img.qammunity.org/2021/formulas/mathematics/high-school/axvju2zaw1nk9cdqm2uvv9ztcisyq6t3gi.png)
![1+r = 1.0424](https://img.qammunity.org/2021/formulas/mathematics/high-school/uxvqf6u087tsaonxr6lkffobk0w4jf1pcq.png)
Hence, growth rate is:
r = 0.0424 = 4.24%