Examples for 8th grade - page 102

  1. Two chords
    circle_chords There is a given circle k (center S, radius r). From point A which lies on circle k are starting two chords of length r. What angle does chords make? Draw and measure.
  2. Line segment
    lines_7 The 4 cm long line segment is enlarged in the ratio of 5/2. How many centimeters will measure the new line segment?
  3. Bricklayers
    murar Seven bricklayers will build the house in 630 days. How many bricklayers do we need to take after 150 days to complete the building for (additional) 336 days?
  4. Digit sum
    cisla_7 How many are three-digit numbers that have a digit sum of 6?
  5. The big clock
    hodiny_4 The big clock hands stopped at a random moment. What is the probability that: a) a small hand showed the time between 1:00 and 3:00? b) the big hand was in the same area as a small hand in the role of a)? c) did the hours just show the time between 21:00.
  6. Electric input power
    resistor_7 Solve problems related to electric power: a) U = 120 V, I = 0.5 A, P =? b) P = 200 W, U = 230 V, I =? c) I = 5 A, P = 2200W, U =?
  7. Lunch
    skola_15 Seven classmates go every day for lunch. If they always come to the front in a different order, will be enough school year to take of all the possibilities?
  8. Water level
    bazen_11 How high is the water in the swimming pool with dimensions of 37m in length and 15m in width, if an inlet valve is opened for 10 hours flowing 12 liters of water per second?
  9. Subsets
    venn5 How many 19 element's subsets can be made from the 26 element set?
  10. The sides
    rectangle_9 The sides of a rectangle are in a ratio of 2:3, and its perimeter is 1 1/4 inches. What are the lengths of its side? Draw it.
  11. Sweater
    colours_3 Dana confuses sweater and wool has a choice of seven colors. In how many ways she can choose from three colors to the sleeves?
  12. Hectoliters
    sudy_4 How many hectoliters of water is in garden barrel with 90 cm diameter and a height of 1.3 m, if it is filled to 80% of its capacity?
  13. How many
    numbers2_41 How many double-digit numbers greater than 30 we can create from digits 0, 1, 2, 3, 4, 5? Numbers cannot be repeated in a two-digit number.
  14. Pool
    bazen_10 The prism-shaped pool is 2 m deep with a bottom of the isosceles trapezoid with base dimensions of 10 m and 18 m and arm legs 7 m long and 5.7 m long. During the spring cleaning, the bottom and walls of the pool must be painted. How many m2 of paint should
  15. Five pupils
    lavicka_1 Five pupils clean 30 chairs one hour before four pupils. How many chairs clean one pupil in 1 hour?
  16. Perimeter of base
    valec_16 The circumference of the base of the rotating cylinder is same as its height. What is the diameter and height of this cylinder with volume 1 liter?
  17. Collect rain water
    valec2_14 The garden water tank has a cylindrical shape with a diameter of 80 cm and a height of 12 dm. How many liters of water will fit into the tank?
  18. Dinning room
    cukriky_14 How many different combinations can we choose if there are 3 soups, 5 kinds of main dish and 2 desserts in the dining room?
  19. Overload
    aircraft-02_10 What overload in g (g-force) has passed the pilot if he accelerated from 0 to 600 km/h in 3 seconds?
  20. In the orchard
    stromy_7 In the orchard, they planted 25 apple trees, 20 pears, 15 plums and 40 marbles. A strong late frost, however, destroyed a fifth of all new trees. Unfortunately, it was all the trees of one kind of fruit. What is the probability that the plums have died out

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