Question

The library at a certain university reported that journal prices had increased by 130% over a period of 10 years. The report concluded that this represented a price increase of 13% each year. If journal prices had indeed increased by 13% each year, what percentage increase would that give over 10 years? (Round your answer as a percentage to the nearest whole number.)

Answer 1

Over 10 years, increasing 15% each year, the prices would have increased 305%.

Explanation:

If journal prices had a constant rate of increase, it's prices could be modeled by the following equation:

In which P(t) is the price after t years, P(0) is the initial price and r is the rate of increase.

If it increased 15% each year.

We would have r = 0.15. So

Over 10 years

The initial price is 100%

4.05P(0) - P(0) = 3.05P(0)

Over 10 years, increasing 15% each year, the prices would have increased 305%.