Question

in hillsboro, the use of landlines has been declining at a rate of 10% every year. if there are 86,652 landlines this year, how many will there be in 12 years?

Answer 1

Answer: A decline of 10% per year means that the number of landlines will be multiplied by 0.9 (100% - 10%) every year.

So, in 12 years the number of landlines will be multiplied by 0.9^12 = 0.531441

So, in 12 years there will be 86,652 * 0.531441 = 46,115.69 landlines.

Rounded to the nearest whole number there will be 46,116 landlines in 12 years.

Explanation:

Answer 2

Answer: 24,473

Step-by-step explanation: This is the formula for exponential decay:

y=a(1–r)t

In this formula, a is the initial amount, r is the rate of decrease expressed as a decimal, t is the elapsed time, and y is the final amount.

solve

Plug in 86,652 landlines for the initial amount, 0.1 for the rate of decrease, and 12 years for the time elapsed.

y

= a(1–r)t

y

= 86,652(1–0.1)12 Plug in values

y

= 86,652(0.9)12 Subtract

y

= 86,652(0.28242…) Simplify

y

= 24,473.08419… Multiply

Round to the nearest whole number.

24,473.08419… → 24,473

To the nearest whole number, there will be 24,473 landlines.