In 2000 the population of a country reached 1 ​billion, and in 2025 it is projected to be 1.2 billion. ​(a) Find values for C and a so that ​P(x)equalsCa Superscript x minus 2000 models the population of a country in year x. ​(b) Estimate the​ country's population in 2010. ​(c) Use P to determine the year when the​ country's population might reach 1.4 billion. ​(a) Cequals nothing ​(Type an integer or decimal rounded to five decimal places as​ needed.)

Respuesta :

Answer:

(a) The value of C is 1.

(b) In 2010, the population would be 1.07555 billions.

(c) In 2047, the population would be 1.4 billions.

Step-by-step explanation:

(a) Here, the given function that shows the population(in billions) of the country in year x,

[tex]P(x)=Ca^{x-2000}[/tex]

So, the population in 2000,

[tex]P(2000)=Ca^{2000-2000}[/tex]

[tex]=Ca^{0}[/tex]

[tex]=C[/tex]

According to the question,

[tex]P(2000)=1[/tex]

[tex]\implies C=1[/tex]

(b) Similarly,

The population in 2025,

[tex]P(2025)=Ca^{2025-2000}[/tex]

[tex]=Ca^{25}[/tex]

[tex]=a^{25}[/tex]                    (∵ C = 1)

Again according to the question,

[tex]P(2025)=1.2[/tex]

[tex]a^{25}=1.2[/tex]

Taking ln both sides,

[tex]\ln a^{25}=\ln 1.2[/tex]

[tex]25\ln a = \ln 1.2[/tex]

[tex]\ln a = \frac{\ln 1.2}{25}\approx 0.00729[/tex]

[tex]a=e^{0.00729}=1.00731[/tex]

Thus, the function that shows the population in year x,

[tex]P(x)=(1.00731)^{x-2000}[/tex]     ...... (1)

The population in 2010,

[tex]P(2010)=(1.00731)^{2010-2000}=(1.00731)^{10}=1.07555[/tex]          

Hence, the population in 2010 would be 1.07555 billions.

(c) If population P(x) = 1.4 billion,

Then, from equation (1),

[tex]1.4=(1.00731)^{x-2000}[/tex]

[tex]\ln 1.4=(x-2000)\ln 1.00731[/tex]

[tex]0.33647 = (x-2000)0.00728[/tex]

[tex]0.33647 = 0.00728x-14.56682[/tex]

[tex]0.33647 + 14.56682 = 0.00728x[/tex]

[tex]14.90329 = 0.00728x[/tex]

[tex]\implies x=\frac{14.90329}{0.00728}\approx 2047[/tex]

Therefore, the country's population might reach 1.4 billion in 2047.

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