A city has a population of 310,000 people. Suppose that each year the population grows by 9%. What will the population be after 13 years?

644,800

Step-by-step explanation:

This can also be solved using the terms of Arithmetic Progressions.

Let the 13 years be number of terms of the sequences (n)

Therefore ;

T₁₃              = a + ( n - 1 )d , where a = 310,000 and d = 9% of 310,000

9% of 310,000 = 9/100 x 310,000

                        = 27,900

so the common difference (d)

                     d = 27,900

Now substitute for the values  in the formula above and calculate

T₁₃              = 310,000 + ( 13 - 1 ) x 27,900

                  = 310,000 + 12 x 27,900

                  = 310,000 + 334,800

                  = 644,800.

The population after 13 years = 644,800.

see explanation

step-by-step explanation:

since the sequence is geometric there is a common ratio r between consecutive terms, that is

r = 4 ÷ - 2 = - 2

r = - 8 ÷ 4 = - 2

r = 16 ÷ 8 = - 2

the next term - 13 must be incorrect as it should be - 32 for the sequence to be geometric.

the first 4 terms are therefore geometric with common ratio r = - 2