Examples for 8th grade - page 13

  1. Radius
    green_circle Determine the radius of the circle, if its perimeter and area is the same number.
  2. Discount
    sales_discount Product has been discounted twice by 19%. What is the total discount given?
  3. Seedcake
    pletenky Seedcake costs 44 cents. How many minimum seedcakes we must buy that we can pay in cash only whole euros?
  4. Madams
    womans During the spring cleaning ladies going to wash windows. Mother takes wash all the windows 5 hours, the grandmother 3 times longer and Paula wash all windows in 2 hours. How many hours will spend washing the windows this "women's team" if working togethe
  5. Diofant equation
    diofantos In the set of integers (Z) solve the equation: ? Write result with integer parameter ? (parameter t = ...-2,-1,0,1,2,3... if equation has infinitely many solutions)
  6. Octahedron - sum
    8sten On each wall of a regular octahedron is written one of the numbers 1, 2, 3, 4, 5, 6, 7 and 8, wherein on different sides are different numbers. For each wall John make the sum of the numbers written of three adjacent walls. Thus got eight sums, which also.
  7. Phone numbers
    old_phone How many 9-digit telephone numbers can be compiled from the digits 0,1,2,..,8,9 that no digit is repeated?
  8. Cuboid
    cuboid_diagonal Determine the dimensions of cuboid a, b, c; if diagonal d=9 dm has angle with edge a α=55° and has angle with edge b β=58°
  9. Cubes
    rubik_cube Cube, which consists of 27 small cubes with edge 4 dm has volume:
  10. Freedom
    family_life In the city are 3/9 of women married for 3/6 men. What proportion of the townspeople is free (not married)? Express as a decimal number.
  11. Square diagonal
    square_diagonal Calculate the length of diagonal of the square with side a = 23 cm.
  12. Vinegar
    vinegar We must dilute 16 liters of 8.8% aqueous vinegar to 4.1% one. How much water is necessary to add?
  13. Clocks
    clocks How long path will walk the end of the clock's minute-hand long 7 cm for 330 minutes? How long will walk in the same time hour-hand?
  14. Parallelogram
    paralleogram Calculate area of the parallelogram ABCD as shown if |AB| = 19 cm, |BC| = 18 cm and angle BAD = 90°
  15. Building
    Taipei_101 How high is the building that throws horizontal shadow 95.4 m long at angle 50°?
  16. Two doctors
    dr_cvach Doctor A will determine the correct diagnosis with a probability 86% and doctor B with a probability 87%. Calculate probability of correct diagnosis if patient is diagnosed by both doctors.
  17. OK circle
    circles2 Calculate the radius (circumradius) of the circle described right triangle with hypotenuse long 33 and one cathetus long 17.
  18. Crossroads
    crossroad The rectangular crossroads comes passenger car and an ambulance, the ambulance left. Passenger car is at 43 km/h and ambulance 52 km/h. Calculate such a relative speed of the ambulance moves to the car.
  19. Wire
    cu_wire One pull of wire is reduced its diameter by 14%. What will be diameter of wire with diameter 19 mm over 10 pulls?
  20. Road embankment
    nasyp_cesta Road embankment has a cross section shape of an isosceles trapezoid with bases 5 m and 7 m, and 2 m long leg. How many cubic meters of soil is in embankment length of 1474 meters?

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