Question

Subscriptions to a fashion magazine have gone down by a consistent 7% each year. If the magazine currently has 28,215 subscribers, how many will there be in 4 years?

Answer 1

21106

Explanation:

You want the number of subscribers in 4 years if it is now 28,215 and decreasing at 7% per year.

Exponential function

The number of subscribers can be modeled by ...

s = s0·(growth factor)^t

where s0 is the number of subscribers now, "growth factor" is the multiplier each year, and t is the number of years. Here the growth factor is ...

growth factor = 1 + growth rate = 1 + (-7%) = 0.93

Application

So, the exponential model for the number of subscribers is ...

s = 28215·(0.93^t)

In 4 years, the number will be ...

s = 28215·(0.93^4) ≈ 21106

There will be 21106 subscribers in 4 years.

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