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| Question 422462:  The population of India is 1.17 billion people and is expected to double in 44 years. The population of China is 1.34 billion people and is expected to double in 67 years. If the trends continue, when will the population of India be the same as China's?
 Answer by lwsshak3(11628)
      (Show Source): 
You can put this solution on YOUR website! The population of India is 1.17 billion people and is expected to double in 44 years. The population of China is 1.34 billion people and is expected to double in 67 years. If the trends continue, when will the population of India be the same as China's? ..
 The formula for population growth:
 N(t)=Noe^kt
 N(t)=population after t years
 No=current population
 k=growth constant
 ..
 finding growth constant using given data and doubling time formula.
 doubling time,T=ln2/k
 k=ln2/T
 for China
 k1=ln2/67
 N(t)=1.34e^k1t
 for India
 k2=ln2/44
 N(t)=1.17e^k2t
 ..
 1.34e^k1t=1.17e^k2t
 taking logarithms of both sides,
 ln(1.34)+k1t(ln(e))=ln(1.17)+k2t(ln(e))
 ln(1.34)+k1t=ln(1.17)+k2t
 ln(1.34)-ln(1.17)=k2t-k1t=t(k2-k1)
 t=ln(1.34)-ln(1.17)/(k2-k1)
 t=25.09 years
 ans:
 The population of India will be the same as that of China in apprximately 25 years.
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