In 2007, the world's population reached 6.7 billion and was increasing at a rate of 1.2% per year. Assume that this growth rate remains constant. (In fact,the growth rate has decreased since 1987.)
(a) Write a formula for the world population as a function of the number of years since 2007. (Note: Use the general exponential function.)
(b) Use your formula to estimate the population of the world in the year 2032. Round your answer to two decimal places.
Ps, I got the answers. My friend did it for me, I just want to know the steps!

Question

In 2007, the world's population reached 6.7 billion and was increasing at a rate of 1.2% per year. Assume that this growth rate remains constant. (In fact,the growth rate has decreased since 1987.) 
 (a) Write a formula for the world population as a function of the number of years since 2007. (Note: Use the general exponential function.)
(b) Use your formula to estimate the population of the world in the year 2032. Round your answer to two decimal places. 
Ps, I got the answers. My friend did it for me, I just want to know the steps!

anonymous · Answer

Every year, the population increases by 1.2%.  We can write this as a series: $$
a_{n+1} = 0.0012a_n
$$We can exant it another term:$$
a_{n+2} = 0.0012a_{n+1} = (0.0012)^2a_n
$$The general pattern is: $$
a_{n+r} = (0.0012)^ra_n
$$

anonymous · Answer

Suppose $n=2007$ and $r$  is the number or years sense then..

anonymous · Answer

$$
a_{2007} = 6.7
$$$$
a_{2007+r} = (0.012)^r6.7
$$

tkhunny · Answer

Aaaa.... NO!  Based on that formula, humans will quickly be swept from the planet by the next opportunistic dominant species.

Please think about 1.012, rather than 0.012.

goformit100 · Answer

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