Examples for 8th grade - page 68

  1. Internal angles
    angle_3 One internal angle of the triangle JAR is 25 degrees. The difference is the size of the two other is 15°. Identify the size of these angles.
  2. Dollars
    children Mama split 760 dollars Jane, Dane and Eva as follows: Jane got three times more than Dane and Dane and got 40 more than Eva. How much does get each of them?
  3. Students
    cinema2 In the front row sitting three students and in every other row 11 students more than the previous row. Determine how many students are in the room when the room is 9 lines, and determine how many students are in the seventh row.
  4. Reducing number
    123 Reducing the an unknown number by 28.5% we get number 243.1. Determine unknown number.
  5. Dining room
    table The dining room has 11 tables (six and eight seats). In total there are 78 seats in the dining room. How many are six-and eight-seat tables?
  6. Painters
    natieraci Five painters painting the fence for eight days. How many days over will take work if paint the fence only four decorators?
  7. Grass seeds
    circular_playground How many kg of grass seed is needed to be sowing a circular field with a diameter of 120 meters when the 1 m2 should be used 0.8 grams seeds?
  8. Pumps A and B
    pump_2 Pump A fill the tank for 12 minutes, pump B for 24 minutes. How long will take to fill the tank if he is only three minutes works A and then both pumps A and B?
  9. Clock Tower
    clock_3 What angle is betwenn hands on Clock Tower when show 17 hours and 35 minutes?
  10. The tent
    stan The tent shape of a regular quadrilateral pyramid has a base edge length a = 2 m and a height v = 1.8 m. How many m2 of cloth we need to make the tent if we have to add 7% of the seams? How many m3 of air will be in the tent?
  11. Bath salts
    salt_1 Bath salt A weighs 900 grams and costs 36,40 CZK. Bath Salts B weighs 1000 grams, but costs 85 CZK. How much is a bath salt A cheaper than B one?
  12. Sum 10
    dices11 What is the probability that two dice throw twice in a row will result the sum of 10?
  13. Forces
    resultant_force Determine the resultant of two perpendicular forces F1 = 560 N and second force of 25% smaller.
  14. Cube diagonals
    krychlicka_1 Determine the volume and surface area of the cube if you know the length of the body diagonal u = 216 cm.
  15. Pears
    hrusky Andrew, Lenka and Rasto have together 232 pears. Lenka has 28 more than Rasto and Rasto pears have 96 more than Andrew. Determine how much each of them has pears.
  16. Peppers
    paprika In the box are yellow (a), green (b) and red (c) peppers. Their amount is in a ratio 2:4:1 . Most are yellow peppers and green the least. Calculate the number of peppers each type if the total number of peppers is 77.
  17. Locomotive
    locomotive_1 Locomotive pulled a train permanent load of 200 kN horizontally along the track of 5km. What work it done?
  18. Sides od triangle
    podobnost Sides of the triangle ABC has length 4 cm, 5 cm and 7 cm. Construct triangle A'B'C' that are similar to triangle ABC which has a circumference of 12 cm.
  19. Salt
    salt_4 Sea water containing 5% salt. How many kg of fresh water necessary to pour into 40 kg of sea water so that the salinity fell to 2%?
  20. Two friends
    beers Two friends met as a good man perish together for a beer. After recovery the most important topics (politics, women, football ...), one asks: - And how many do you have children? - I have 3 children. - And how many years have? Friend already not want to an

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.