The reason why I don't agree with Priya is because 25 Inch side blocks are BIGGER than 15 inch side blocks. That means that it will take less amount of 25 inch side blocks to fill up the volume of the rectangular prism rather than 15 inch side blocks.
(I'm sorry, I don't know what was your previous question, so I can't answer that part. If you comment it below, I will do it!)
A=Pe^(rt) when it is a decay, make r negative P=23781 and r=-0.032 and t=17 A=23781e^(-0.032*17) A=23781e^(-0.554) A=13803.01 so about 13803 people is the population after 17 years