Logarithm - 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. Dice
    dices How many times must throw the dice, the probability of throwing at least one three was greater than 90%?
  3. Sequence
    seq Calculate what member of the sequence specified by ? has value 643.
  4. Exp
    old_calculator If ?, then n is:
  5. Demographics
    population The population grew in the city in 10 years from 14000 to 27500. What is the average annual percentage increase of population?
  6. Compound interest
    exponential_usd Calculate time when deposit in the bank with interest 2% p.a. doubles.
  7. Logarithmic equation
    nat_log_ln Solve equation: log11(10x + 28) = 0
  8. Logarithm
    log_hat Determine the number whose decimal logarithm is -4.5.
  9. 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.
  10. 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?
  11. 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.
  12. Seating rules
    school_class In a class are 22 seats but in 2.B class are only 14 students. How many ways can student seat? (The class has 11 benches. A bench is for a pair of students.) Result (large number) logarithm and thus write down as powers of 10.
  13. 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.
  14. Gain
    solar Find the gain whenever the output power is 11x the input power.
  15. Coordinate
    exp_ln Determine missing coordinate of the point M [x, 108] of the graph of the function f bv rule: y = 3x
  16. Log
    log if ?, what is b?
  17. 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.
  18. Car value
    car_old The car loses value 15% every year. Determine a time (in years) when the price will be halved.
  19. 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?
  20. Future of libraries
    library You know that thanks to the Internet, electronic communications and developing online resources on the Internet annually declining number of traditional readership by 15%. These deal is irreversible evolutionary shift from old books from libraries to immed

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