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October 2nd, 2017, 10:14 AM  #1 
Newbie Joined: Oct 2017 From: USA Posts: 1 Thanks: 0 
If an increased rate of death in a population of 200 million people was noted (89% in 14 years), how many years would it take before they were all dead? And would the percentage increase over this time, or decrease? This is not a problem for school; it is a question I have about mortality expectancy, and I may not be presenting this correctly as I am certainly not a mathematician! Last edited by skipjack; October 15th, 2017 at 04:24 PM. 
October 2nd, 2017, 01:40 PM  #2 
Global Moderator Joined: May 2007 Posts: 6,540 Thanks: 591 
Question not clear. 89% of what? Second question can't be answered without further information.

October 2nd, 2017, 09:32 PM  #3 
Global Moderator Joined: Dec 2006 Posts: 19,177 Thanks: 1644  
October 2nd, 2017, 09:50 PM  #4 
Math Team Joined: Jul 2013 From: काठमाडौं, नेपाल Posts: 878 Thanks: 60 Math Focus: सामान्य गणित 
What is the initial rate of death?

October 3rd, 2017, 05:48 AM  #5 
Math Team Joined: Oct 2011 From: Ottawa Ontario, Canada Posts: 12,762 Thanks: 860  
October 15th, 2017, 11:49 AM  #6 
Senior Member Joined: Oct 2013 From: New York, USA Posts: 606 Thanks: 82 
There is no information about the death rate that will tell you the age of death of one specific person. Deaths are similar (identical?) to independent events, which do not have guarantees. For example, you can calculate how many coins you need to flip to have a 99% chance of at least 1 head, but you can't calculate amount for a 100% chance. You cannot calculate how long until every person in a group of 200 million will be dead.

October 15th, 2017, 02:00 PM  #7 
Math Team Joined: Dec 2013 From: Colombia Posts: 7,330 Thanks: 2456 Math Focus: Mainly analysis and algebra 
There is no definitive statement as to how long before everyone is dead (if ever). These models never reach 100% exactly. It's a consequence of having a death rate. Eventually the model predicts that approximately 1 person remains. What happens next? 89% (extraordinarily high, but it's your number) of that person dies? What does that mean? Such models are usually used for long term qualitative analysis: extinction or some type of survival (often periodic); or shorter term quantative analysis (the population will reduce by x% over y years). Of course, when the predicted population is much less than 1 (0.01, say) you can be reasonably sure that they've all died, but the simplifying errors in the model itself make accurately pinpointing precise populations or when they'll happen impossible. 