Diketahui : Po = 40.400 (1965) n = 25 th Pn = 59.538 (1990) r = ?

Jawab :

1. Geometris

Pn = Po (1+r)n

Pn ------ = (1+ r)n

Po

log Pn- log Po = n log (1+ r)

log Pn - log Po------------------- = log (1+ r) n

log 59.538 - log 40.400 ------------------------------- = log (1+ r)

25

0,1684128-------------- = log (1+ r) 25

0,996736512 = log (1+ r)

Anti log 0,996736512 = 1+ r

1,0156323 = 1+ r

r = 1,0156323 – 1

r = 0,0156323 atau

r = 1,56 %

2. Eksponensial

Pn = Po ern

Pn ------ = ern

Po

59.538 ----------- = ern

40.400

1,473712871= ern

log 1,473712871 = 25 . r. log 2,7182818

0,168412876 = 25 . r . 0,43429419

r = 0,01551

r = 1,55%

3. Waktu lipat dua

70n = ----------- r

70n = ----------- = 45, 16

1,55

Jadi 1965 + 45 = 2010 pada tahun 2010 jumlah penduduk menjadi 80.800 orang