Question

In Livingston, the use of landlines has been declining at a rate of 20% every year. of there are 23,000 landlines this year, many will there be in 6 years?? if necessary, round your answer to the nearest whole number

Answer 1

In 6 years there are

Apply N1= 230000

N = N1 - N1•20/100 - N1• (20/100)^2 - N1•(20/100/^3 - N1•(20/100)^4 - N1(20/100)^5 - N1•(20/100) ^6

Then replace 20/100= 1/5

N= 23000 - 23000 • ( 1/5 + 1/25 + 1/125/ + 1/625 + 1/3125 + 1/15625 )

N= 23000 - 5750 = 17250

Then answer is

In 6 years there will be 17250 landlines