Exponential equation - examples

  1. Photocopier
    picture A photocopier enlarges a picture in the ratio 7:4. How many times will a picture of size 6cm by 4cm be enlarged to fit on a 30cm by 20 cm page?
  2. Sequence
    seq Calculate what member of the sequence specified by ? has value 643.
  3. Exp
    old_calculator If ?, then n is:
  4. Demographics
    population The population grew in the city in 10 years from 14000 to 27500. What is the average annual percentage increase of population?
  5. Compound interest
    exponential_usd Calculate time when deposit in the bank with interest 2% p.a. doubles.
  6. Lion or virgin
    1_kcs 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.
  7. Crystal
    crystal Crystal grows every month 2.9 promile of its mass. For how many months to grow a crystal from weight 310 g to 482 g?
  8. Half life
    Bi Determine the half life of bismuth, when bismuth weight from the original weight of 32 g was only 2 grams in 242 minutes.
  9. Geometric sequence 3
    sequence In geometric sequence is a6 = 77760; a7= 466560; sn=93310. Calculate the first item a1, quotient q and n - number of members by their sum s_n.
  10. Coordinate
    exp_ln Determine missing coordinate of the point M [x, 108] of the graph of the function f bv rule: y = 3x
  11. Log
    log if ?, what is b?
  12. Insert into GP
    archimedes_1 Between numbers 5 and 640 insert as many numbers to form geometric progression so sum of the numbers you entered will be 630. How many numbers you must insert?
  13. When will I be a millionaire?
    milionar_kedy Chris monthly send 150 euros to the bank, which he deposits bear interest of 2.1% p.a. Calculate how many months must Chris save to save 1000000 euros? Inflation, interest rate changes or bank failures ignore.
  14. Car value
    car_old The car loses value 15% every year. Determine a time (in years) when the price will be halved.
  15. Radioactivity
    radioactivity After 115 hours decreases the activity of a radioactive substance to 1/9 of the initial value. What is the half-life of the substance?
  16. Exponential equation
    exp Solve exponential equation (in real numbers): 12-x-10=18
  17. To the cinema
    tree 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.
  18. Interest
    MoneyHouse What is the annual interest rate on your account if we put 12700 and after 148 days received 12982.6?
  19. Exponential equation
    exp In the set R solve the equation: ?
  20. Sum-log
    complex_log The sum of two numbers is 10, the sum of their logarithms (base 10) is 1.1. Determine these numbers.

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