Logarithm + exponential equation - examples

1. 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?
2. 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.
3. Compound interest
Calculate time when deposit in the bank with interest 2.5% p.a. doubles.
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. Geometric sequence 3
In geometric sequence is a8 = 312500; a11= 39062500; sn=1953124. Calculate the first item a1, quotient q and n - number of members by their sum s_n.
6. Exp
If ?, then n is:
7. Sequence
Calculate what member of the sequence specified by ? has value 86.
8. 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.
9. 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
10. Sum-log
The sum of two numbers is 32, the sum of their logarithms (base 10) is 2.2. Determine these numbers.
11. To the cinema
Jane at 8 am got message that all 1093 school pupils will 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 all the children in.
12. Exponential equation
In the set R solve the equation: ?
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?
14. Exponential equation
Solve exponential equation (in real numbers): 98x-2=9
15. Coordinate
Determine missing coordinate of the point M [x, 120] of the graph of the function f bv rule: y = 5x
16. Car value
The car loses value 15% every year. Determine a time (in years) when the price will be halved.
17. Lion or virgin
We toss coin, every throw fits lion or a virgin with equal probability 1/2. Determine how much at least we have to make throws that with probability 0.9 lion fell at least once.
18. Log
if ?, what is b?
19. Geometric sequence
In the geometric sequence is a4 = 20 a9 = -160. Calculate the first member a1 and quotient q.
20. The city 3
The city has 22,000 residents. How long it is expected to have 25,000 residents if the average annual population growth is 1.4%?

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