Logarithm + time - practice problems - last page
Number of problems found: 35
- Microorganisms
The first generation of microorganisms has a population of 13500 members. Each subsequent generation is 11/10 times the previous one. Find out how many generations will reach at least three times members of the first generation. - One-eighth 6206
Water lilies grow on the pond, and their number doubles every day. We will cover the whole level in 12 days. In how many days will one-eighth of the surface be covered? - Water lilies
Water lilies are growing on the pond, and their number is doubling every day. The whole layer is covered in 12 days. How many days will it cover eight layers? - Exponential warm
Suppose that a body with temperature T1 is placed in surroundings with temperature T0 different from that of T1. The body will either cool or warm to temperature T(t) after time t, in minutes, where T(t)=T0 + (T1-T0)e^(-kt). If we placed jello salad at 30
- Interest 6047
Mr. Demikát took out a loan worth 5,000 euros from the bank with an interest rate of 12 percent. How many months will it repay if the monthly payment is 80 euros? - Precision 3390
The price of the device is reduced by one-fifth every year. How long before the price of the device drops to one-tenth of the price? Specify years and months with precision. - To the cinema
Jane at 8 AM got a message that all 1093 school pupils would go to the cinema. Within 20 min she said it to the three friends. Each of them again for 20 minutes said to the other three. In this way, the message spread further. At what time do all the scho - Car value
The car loses value by 15% every year. Determine a time (in years) when its price will halve. - 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 159,000 inhabitants. 25 years ago, there were 158,000. How many people will live in a city in 10 years if the population's average rate is as in previous years? - Crystal
The crystal grows every month 1.2 permille of its mass. How many months to develop a crystal from weight 177 g to 384 g? - Demographics
The population grew in the city in 10 years from 30000 to 34000. What is the average annual percentage increase in population? - Compound interest
Calculate the time when the deposit in the bank with interest 2.6% p.a. doubles. - Radioactivity
After 548 hours decreases, the activity of a radioactive substance to 1/9 of the initial value. What is the half-life of the substance?
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