Latest problems

  1. Regrouping
    mixed_7 Subtract mixed number with regrouping: 11 17/20- 6 19/20
  2. Is right-angled
    rt_sqrt_1 Can a triangle with the sides of sqrt 3, sqrt 5 and sqrt 8 (√3, √5 a √8) be a right triangle?
  3. Isosceles
    rr_lichobeznik_1 Isosceles trapezium ABCD ABC = 12 angle ABC = 40 ° b=6. Calculate the circumference and area.
  4. 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.
  5. 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?
  6. Ophelia
    teplomer_9 Ophelia recorded the temperature of a cold store every two hours. 1. At 6am it was -4°C and at 8am it was -1°C. By how much did the temperature rise? 2. The temperature went up by 5°C in the next two hours. .What was the temperature at 10am?
  7. Double ladder
    dvojak The double ladder is 8.5m long. It is built so that its lower ends are 3.5 meters apart. How high does the upper end of the ladder reach?
  8. Tropical, mild and arctic
    tropic How many percents of the Earth's surface lies in the tropical, mild and arctic range? The border between the ranges is the parallel 23°27 'and 66°33'.
  9. Cube into sphere
    sphere_in_cylinder_1 The cube has brushed a sphere as large as possible. Determine how much percent was the waste.
  10. Digit sum
    cisla_7 How many are three-digit numbers that have a digit sum of 6?
  11. Hemispherical hollow
    odsek The vessel hemispherical hollow is filled with water to a height of 10 cm =. How many liters of water are inside if the inside diameter of the hollow is d = 28cm?
  12. Square into three rectangles
    stvorcove-cisla Divide the square with a side length of 12 cm into three rectangles with have the same circumference so that these circumferences are as small as possible.
  13. Right triangle
    rt_A Calculate the length of the remaining two sides and the angles in the rectangular triangle ABC if a = 10 cm, angle alpha = 18°40'.
  14. Two rectangles
    rectangles2_2 I cut out two rectangles with 54 cm², 90 cm². Their sides are expressed in whole centimeters. If I put these rectangles together I get a rectangle with an area of 144 cm2. What dimensions can this large rectangle have? Write all options. Explain your calcu
  15. Prove
    two_circles_1 Prove that k1 and k2 is the equations of two circles. Find the equation of the line that passes through the centers of these circles. k1: x2+y2+2x+4y+1=0 k2: x2+y2-8x+6y+9=0
  16. CuSO4 mixture
    chemia_2 How many grams of solid CuSO4 we have to add to 450g of 15% CuSO4 solution to produce a 25% solution?
  17. Sum of inner angles
    angle-sum-of-polygon Prove that the sum of all inner angles of any convex n-angle equals (n-2) . 180 degrees.
  18. 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.
  19. Sandbox
    sand_2 Sandbox has area of 32 sq ft and length of 4 1/2 ft. What is width of sandbox.
  20. Digits
    seq_5 Show that if x, y, z are 3 consecutive nonzero digits, zyx-xyz = 198, where zyx and xyz are three-digit numbers created from x, y, z.

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