What is the annual rate of growth of population of bacteria which has increased by 25% in the first hour 30% in the second hour and 10% in the third hour?
- None of these
The Usual Method
Annual rate of growth = Geometric Mean (GM) as shown below:
= = 1.21
i.e. 21 %
Estimated Time to arrive at the answer = 120 seconds as this method requires finding a cube root which can best be done in an iterative manner without the use of a calculator
Simply find the Arithmetic Mean (AM) of the three percentage values
i.e. = = 21
We already know that AM > GM and that the difference is small when the individual values are ‘near’ each other. Thus the actual answer has to be less than 21.67% but close to it. Hence, the answer must be 21% or option ‘2’.