Logarithm - math word problems

  1. Growth of wood
    wood The annual growth of wood in the forest is estimated at 2%. In how many years will make the forest volume double?
  2. Pilsen circus
    cirkus 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
  3. An investment
    exp_growth2 How long will it take for an investment to double at a simple interest rate of 5.10% p. A. ? Express the answer in years and months, rounded up to the next month.
  4. Powers 3
    exp_4 2 to the power of n divided by 4 to the power of -3 equal 4. What is the vaule of n?
  5. Microorganisms
    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.
  6. Intercept with axis
    log_10 F(x)=log(x+4)-2, what is the x intercept
  7. Geometric progression
    exp_1 In geometric progression, a1 = 7, q = 5. Find the condition for n to sum first n members is: sn≤217.
  8. Water lilies
    lekno_2 Water lilies are growing on the pond and their number is doubled every day. The whole layer is covered in 12 days. How many days will it cover 8 layers?
  9. Exponential warm
    teplomer_6 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 jello salad with 30 degre
  10. Exponential equation
    exp_8 Solve for x: (4^x):0,5=2/64.
  11. 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?
  12. Exponential equation
    exp Find x, if 625 ^ x = 5 The equation is exponential because the unknown is in the exponential power of 625
  13. The city 3
    city_2 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%?
  14. Car value
    car_old The car loses value 15% every year. Determine a time (in years) when the price will be halved.
  15. 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
  16. 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.
  17. Geometric sequence
    cralici In the geometric sequence is a4 = 20 a9 = -160. Calculate the first member a1 and quotient q.
  18. 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.
  19. Sum-log
    complex_log The sum of two numbers is 32, the sum of their logarithms (base 10) is 2.2. Determine these numbers.
  20. Seating rules
    school_class In a class are 24 seats but in 7.B class are only 18 students. How many ways can student seat? (The class has 12 benches. A bench is for a pair of students.) Result (large number) logarithm and thus write down as powers of 10.

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