# Geometric progression + time - math problems

#### Number of problems found: 31

- The half life

The half-life of a radioactive isotope is the time it takes for a quantity of the isotope to be reduced to half its initial mass. Starting with 145 grams of a radioactive isotope, how much will be left after 3 half-lives? - Savings

The depositor regularly wants to invest the same amount of money in the financial institution at the beginning of the year and wants to save 10,000 euros at the end of the tenth year. What amount should he deposit if the annual interest rate for the annua - Volume of wood

Every year, at the same time, an increase in the volume of wood in the forest is measured. The increase is regularly p% compared to the previous year. If in 10 years the volume of wood has increased by 10%, what is the number p? - Growth of wood

The annual growth of wood in the forest is estimated at 2%. In how many years will make the forest volume double? - Five harvests

In the seed company, they know that, out of 100 grains of a new variety, they get an average of 2000 grains after harvest. Approximately how many grains do they get out of 100 grains after five harvests? - Pilsen circus

The arrival of the circus in Pilsen was seen in the morning at 08:00 by a citizen of the city. He passed this information on 08:15 to three other residents of the city. Each of these three people then informed the other three residents at 08:30, and again - Pilsen Region

Between 2000 and 2001, 14 per mille of the population decreased in the Pilsen Region. In 2000, the Pilsen Region had 551281 inhabitants. If the declining trend continues the same (i. E. , 14 per mille of inhabitants per year), how many inhabitants will th - Investment 2

Jack invested $5000 in a 5-month term deposit at 4.7% p. A. . At the end of the 5-months, jack reinvested the maturity value from the first deposit into an 11-month term deposit at 7.3% p. A. What is the maturity value at the end of the second term deposi - Curiosity factor

A blogger starts a new website, initially the number of the traffic is 293 due to their curiosity factor. The business owner estimated that the traffic will increase by 2,6% per week. What will be the number of it in week 5?. - Microorganisms

The first generation of micro-organisms has a population of 13500 members. Each next generation is 11/10 times the previous one. Find out how many generations will reach at least three times members of the first generation. - The crime

The crime rate of a certain city is increasing by exactly 7% each year. If there were 600 crimes in the year 1990 and the crime rate remains constant each year, determine the approximate number of crimes in the year 2025. - Compound interest

Compound interest: Clara deposited CZK 100,000 in the bank with an annual interest rate of 1.5%. Both money and interest remain deposited in the bank. How many CZK will be in the bank after 3 years? - Population

What is the population of the city with 3% annual growth, if in 10 years the city will have 60,000 residents? - Miraculous tree

Miraculous tree grows so fast that the first day increases its height by half the total height of the second day by the third, the third day by a quarter, etc. How many times will increase its height after 6 days? - The city 2

Today lives 60000 citizens in city. How many citizens can we expect in 8 years if their annual increase is 2.9%? - Half life

Determine the half life of bismuth, when bismuth weight from the original weight of 32 g was only 2 grams in 242 minutes. - Population

The town has 65,000 inhabitants. 40 years ago there were 157,000. How many people will live in town in 10 years if the average rate in population is as in previous years? - Deposit

If you deposit 719 euros the beginning of each year, how much money we have at 1.3% (compound) interest after 9 years? - Crystal

Crystal grows every month 1.2 promile of its mass. For how many months to grow a crystal from weight 177 g to 384 g? - Compound interest

Calculate time when deposit in the bank with interest 2.5% p.a. doubles.

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