# Percentages + exponential equation - examples

1. An investment
How long will it take for an investment to double at a simple interest rate of 5.10% p. A. ? Express the answer in years and months, rounded up to the next month.
2. Crystal
Crystal grows every month 1.9 promile of its mass. For how many months to grow a crystal from weight 136 g to 384 g?
3. When will I be a millionaire?
Barry monthly send 280 euros to the bank, which he deposits bear interest of 2.1% p. A. Calculate how many months must Barry save to save 1000000 euros? Inflation, interest rate changes, or bank failures ignore.
4. Demographics
The population grew in the city in 10 years from 42000 to 54500. What is the average annual percentage increase of population?
5. Computer revolution
When we started playing with computers, the first processor, which I remember was the Intel 8080 from 1974, with the performance of 0.5 MIPS. Calculate how much percent a year rose CPU performance when Intel 486DX from 1992 has 54 MIPS. What
6. Interest
What is the annual interest rate on your account if we put 32790 and after 176 days received 33939.2?
7. Car value
The car loses value 15% every year. Determine a time (in years) when the price will be halved.
8. Repay, interest, loan
Ramchacha takes a loan amount of 240000 from a bank for constructing a house at the rate of simple interest of 12% per annum. After 1 yr. of taking the loan he rents the house at the rate of 5200 per month. Determine the number of years he would take to re
A radioactive material loses 10% of its mass each year. What proportion will be left there after n=6 years?
10. Investment
1000\$ is invested at 10% compound interest. What factor is the capital multiplied by each year? How much will be there after n=12 years?
11. Annual pension
Calculate the amount of money generating an annual pension of EUR 1000, payable at the end of the year and for a period of 10 years, shall be inserted into the bank to account with an annual interest rate of 2%

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