Examples for 8th grade

  1. Bag of peanuts
    oriesky Joe eat 1/3 of a bag of peanuts, mark eat 1/4 of the remaining in the bag of peanuts, Alvin eat 1/2 of the remaining bag of peanuts, peter eat 10 peanuts, there are 71 peanuts left. Hon many peanuts were in the bags?
  2. Pine's forest
    borovica There were so many pines in the forest that if they were sequentially numbered 1, 2, 3,. .. , would use three times more digits than the pine trees alone. How many pine trees were there in the forest?
  3. Working alone
    workers Tom and Chandri are doing household chores. Chandri can do the work twice as fast as Tom. If they work together, they can finish the work in 5 hours. How long does it take Tom working alone to do the same work?
  4. Two math problems
    coins 1) The sum of twice a number and -6 is nine more than the opposite of that number. Find the number. 2) A collection of 27 coins, all nickels, and dimes, is worth $2.10. How many of each coin are there? The dime, in United States usage, is a ten-cent coi
  5. Ratio of volumes
    cylinder If the heights of two cylindrical drums are in the ratio 7:8 and their base radii are in the ratio 4:3. What is the ratio of their volumes?
  6. Three tributaries
    bazen It is possible to fill the pool with three tributaries. The first would take 12 hours, the second 15 hours, and the third 20 hours. The day before the summer season began, the manager opened all three tributaries simultaneously. How long did it take to fi
  7. Temperature difference 2
    teplomer The temperature in London on new year’s day is -2 degree Celsius. The temperature in Moscow on the same day is -14 degree Celsius, what is the temperature difference between the two cities?
  8. Two cities
    motorbike Cities A and B are 200 km away. At 7 o'clock from city A, the car started at an average speed of 80 km/h, and from B at 45 min later the motorcycle is started at an average speed of 120 km/h. How long will they meet and at what distance from the point A i
  9. A kite
    kite2 ABCD is a kite. Angle OBC = 20° and angle OCD = 35°. O is the intersection of diagonals. Find angle ABC, angle ADC and angle BAD.
  10. Ratio of sides
    described_circle2 Calculate the area of a circle that has the same circumference as the circumference of the rectangle inscribed with a circle with a radius of r 9 cm so that its sides are in ratio 2 to 7.
  11. Two cubes
    cubes2 The surfaces of two cubes, one of which has an edge of 22 cm longer than the second are differ by 19272 cm2. Calculate the edge length of both cubes.
  12. Rectangular trapezoid
    rt_trapezium In a rectangular trapezoid ABCD with right angles at vertices A and D with sides a = 12cm, b = 13cm, c = 7cm. Find the angles beta and gamma and height v.
  13. Sphere VS
    gule Find the surface and volume of a sphere that has a radius of 2 dm.
  14. Six workers
    workers Six workers planned to repair the roof in 5 days. After two days, two workers get sick. How long will the remaining workers complete the roof at the same rate of work?
  15. One three
    dice We throw two dice. What is the probability that max one three falls?
  16. A sculptor
    statue A sculptor is duplicating a statue based on an original statue. If the scale factor of the replication is 3.2, will the new statue be larger or smaller than the original statue (enter 1 = larger, 0= smaller)
  17. Four painters
    painter The company sent four painters to paint the school. They should be done in 12 days. After three days, one painter got ill. How long will the remaining painters paint the school?
  18. Metal tube
    pipe2 Calculate the metal tube mass 8dm long with the outer radius 5cm and the inner radius 4.5cm and 1cm3 of this metal is 9.5g.
  19. Winch
    bubon The steel rope has a diameter of 6mm and a length of 20m. We are winding on drum width 60mm, starting diameter 50mm. What is the final diameter after winding?
  20. Delayed clock
    clock-night-schr Michael put a new battery into his watch at midnight. However, they are 5 seconds late each minute. How many hours does the watch show in 24 hours?

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