# Examples for 8th grade - page 99

1. Cube surface and volume Find the surface of the cube with a volume of 27 dm3.
2. The tank The tank had 9 inflows to be filled in 21 days. After 9 days, 3 trips out. How many days did the remaining 6 tributaries fill the tank?
3. Tourist A tourist walked an average speed of 3.5 km/h route in 6 hours. Calculate how many hours he would have passed at an average speed of 5.5 km/h.
4. Spending If spends 25% of my net pay of \$922.28 on entertainment. How much money is that?
5. Right triangle Calculate the length of the remaining two sides and the angles in the rectangular triangle ABC if a = 10 cm, angle alpha = 18°40'.
6. Four pavers Four pavers would pave the square in 18 days. How many pavers do you need to add to done work in 12 days?
7. Bricks pyramid How many 50cm x 32cm x 30cm brick needed to built a 272m x 272m x 278m pyramid?
8. Big cube Calculate the surface of the cube, which is composed of 64 small cubes with an edge 1 cm long.
9. 7 digit number If 3c54d10 is divisible by 330, what is the sum of c and d?
10. Flowerbed Ondra digs the bed in 20 minutes. Cuba in 30 minutes. For how long do they dig together?
11. Ratio of sides 2 The ratio of the side lengths of one square to another is 1:2. Find the ratio of the area of the two squares.
12. The painter In order for the painter to get the desired color, he must mix green and yellow in a ratio of 4: 7. If it has 28 l of green color, how many liters of yellow color should he add? How many liters of mixed color does he get?
13. Body diagonal Calculate the length of the body diagonal of the 6cm cube.
14. Soldier An experienced soldier digs a good trench in 30 hours. Two soldiers dug the same trench each 40 hours. How many hours will the ditch dig all three together?
15. Budget plan In the construction of the building, the planned budget exceeded 13%, which was 32,500 euros. How many euros cost built the building?
16. Is right triangle or not If right triangle ABC, have sides a=13, b=11.5, c=22.5. Find area.
17. Workers Two workers will construct the stage at the festival in 54 hours. Organizers need to shorten the assembly time by 42 hours. How many workers must the assembly company send?
18. Cube diagonals The cube has a wall area of 81 cm square. Calculate the length of its edge, wall, and body diagonal. A meter pole perpendicular to the ground throws a shadow of 40 cm long, the house throws a shadow 6 meters long. What is the height of the house? Find radius of circle using pythagorean theorem where a=9, b=r, c= 6+r