Examples for 8th grade - page 42

  1. Percentage of waste
    14 In a square plate with side 42 cm we cut 4 same circles. Calculate the percentage of waste.
  2. Workers
    zamkova_dlazba Ten workers must pave road street for 22 working days. After four days were for speeding up work added two more workers. a) After how many work days now workers completes the paved road? b) How many working days it took a total paved road?
  3. Water pool
    basen_2 Pool with volume 990hl completely filled, if water flows by one tap 8 hours and by second tap 6 hours. First tap give 10hl more than second per hour. How many hl flows in each of them in an hour?
  4. Lamp cone
    lampa Calculate the surface of a lamp shade shaped of a rotary truncated cone with base diameter 32 cm and 12 cm and height 24 cm.
  5. Thales
    circles_1 Calculate the length of the Thales' circle described to right triangle with hypotenuse 44 cm.
  6. Tree
    strom How tall is the tree that observed in the visual angle of 52°? If I stand 5 m from the tree and eyes are two meters above the ground.
  7. Bakery
    bread_1 How heavy must prepare bread at a bakery if lose during baking 14% of water and after baking must have 1.6 kg? (Calculate to the nearest gram)
  8. The dam
    prehrada-orlik The water reservoir is filled with first tributary for 25 hours second tributary for 35 hours. Some time were both inlets open, then a second tributary closed and the tank was filled in four hours. What time water flowed from both tributaries? (Expressed i
  9. Slope
    lines.JPG Calculate the slope of a line that intersects points (38,-23) and (-93,5).
  10. Annulus
    medzikruzie.JPG Two concentric circles form an annulus of width 10 cm. The radius of the smaller circle is 20 cm. Calculate the content area of annulus.
  11. Powers
    math_fun Is true for any number a,b,c,d equality:? ?
  12. Cosine
    cosine The point (21, 20) is on the terminal side of angle θ. cos θ = ?
  13. Wood
    timber Wood contains 12% water. 1 m3 of wood weighs 650 kg. How many liters of water it contains?
  14. Cars motion
    AB From point A car start at the speed of 90 km/h. Against it departs from the point B at the same time another car at 60 km/h. For how long and where they met if the distance between A and B is 180 km?
  15. Lie/do not lie
    lines_and_points The function is given by the rule f(x) = -x-12. Determine whether point D[-4; 2] lies on this function. Solve graphically or numerically and give reasons for the your answer.
  16. Chord MN
    lyra_tetiva Chord MN of circle has distance from the center circle S 118 cm. Angle MSN is 41°. Determine the radius of the circle.
  17. Decomposition
    prime_factorization Make decomposition using prime numbers of number 355. Result write as prime factors (all, even multiple)
  18. Mixing
    FMCG If we mix 5 kg of goods of one kind and 3 kg second one, resulting mixture cost 16.50 EUR/kg. If these quantities are mixed in reverse - first three kilograms and 5 kilograms second cost of mixture is 18.50 EUR/kg. What is the price of one kg of goods of.
  19. Tractors
    tractor 6 tractors started plowing the field that them together take 12 days. Agronomist hesitates to A) after 2 days to withdraw 2 tractors, or B) after 3 days to withdraw 3 tractors. Help him which of these two cases will be plowing done sooner.
  20. 6 regular polygon
    hexagon_2 It is given 6 side regular polygon whose side is 5 cm. Calculate its content area. Compare how many more cm2 (square centimeters) has a circle in which is inscribed the 6-gon.

Do you have interesting mathematical example that you can't solve it? Enter it and we can try to solve it.



To this e-mail address we will reply solution; solved examples are also published here. Please enter e-mail correctly and check whether you don't have a full mailbox.