Examples for 8th grade - page 63

  1. Coal
    coal If the daily consumption of 1.6 tons of coal, it is sufficient to supply the boiler for 42 days. How long is sufficient to supply when will burn only 1.2 tons of coal a day ?
  2. 7 roses
    roses_1 Peter buys 7 roses. When he pay for it left him 4 euro. If he bought 5 roses left him 40 euros. How many euros had Peter before buying?
  3. Mother and daughter
    kresba_1 The ratio of years mother and daughter is 5:2. After 7 years the ratio is 2: 1. How many years ago daughter was born?
  4. Runners circle
    runners Pepa circles the track in 36 seconds. Kamil in 42 seconds. They started together. How many seconds will meet again at the start?
  5. Three numbers
    numbers_9 Find three numbers so that the second number is 4 times greater than the first and the third is lower by 5 than the second number. Their sum is 67.
  6. Solutions
    bilde How much 60% solution and how much 35% solution is needed to create 100 l of 40% solution?
  7. Two rooms
    clean_1 Woman cleans the room in 30 minutes a man in 90 minutes. How long will take they clean two rooms?
  8. Gearing
    prevod Gearing consists of two wheels, one is 88 and second 56 teeth. How many times turns smaller wheel to fit the same teeth as in the beginning? How many times will turn biggest wheel?
  9. 4 pipes
    roury The tank flows out by 4 pipes in 6 hours 120 hl water. How much water flows out of 5 pipes of the same diameter in 14 hours?
  10. Concrete block
    abc Determine the volume of concrete block whose one edge of the base has a length 3 meters, body diagonal is 13 meters and its height is 12 meters.
  11. Mrs XY
    crime Mrs Novak is employed. In January 2015 the gross income reached € 1348. Insurance is a 323.52 euros, and income taz 153.67 euros. Employer precipitated Mrs. Novak in recent clashes € 115, of which 57 euro for the savings account, and 58 euros for repayment
  12. Rhumbline
    kosodélník Find circumference and area of the rhumbline ABCD if the short side AD of which has a length of 5 cm, and the heel of the height from D leading to the AB side divides the AB side into two sections of 3 cm and 4 cm.
  13. Sinus
    sine_cosine Determine the smallest integer p for which the equation 4 sin x = p has no solution.
  14. Probability - tickets
    zreby What is the probability that when you have 25 tickets in 5000 that you wins the first (one) prize?
  15. Prism
    hranol_3bokovy_1 Find the volume and surface area of prism with base of an equilateral triangle with side 7 dm long and the body height of 1.5 m.
  16. Painters
    natieraci Five painters painting the fence for eight days. How many days over will take work if paint the fence only four decorators?
  17. Cube 6
    water_cube Surface area of one wall cube is 1600 cm square. How many liters of water can fit into the cube?
  18. Coffee shop
    coffee-beans To the coffee shop brought 2 types of coffee totally 50 kg. The first type was CZK 220 per kilogram, coffee second type 300 CZK per 1 kg. For all the coffee trader earned CZK 12,000. How many kilograms of coffee of first type and how many kilograms of cof
  19. Square garden
    garden_4 On the plan with a scale of 1:1500 is drawn as a square garden with area 81 cm2. How many meters is long garden fence? Determine the actual acreage gardens.
  20. Scale of the map
    meritko Determine the scale of the map if the actual distance between A and B is 720 km and distance on the map is 20 cm.

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.