# Examples for 7th grade (seventh) - page 80

1. Bottle A company wants to produce a bottle whose capacity is 1.25 liters. Find the dimensions of a cylinder that will be required to produce this 1.25litres if the hight of the cylinder must be 5 times the radius.
2. Marriage sttus In our city, there are 3/5 of the women married to 2/3 of the men. Find what part of the population is free.
3. Pool tiles The pool is 25m long, 10m wide and 160cm deep. How many m2 of tiles will be needed on the walls and the pool? How many pieces of tile are needed when 1 tile has a square shape with a 20cm side? How much does it cost when 1m2 of tiles costs 258 Kc?
4. Three segments The circle is divided into 3 segments. Segment A occupies 1/4 of the area, segment B occupies 1/3 of the area. What part is occupied by section C? In what proportion are areas A: B: C?
5. Clothes Danka and Janka collect clothes. Danka had 9 more than Janka, so she gave her 7. Which now has more cloth and how many?
6. Symbols If 2*3 = 60 ; 3*4 = 120 and 4*5 = 200, what is 2*5?
7. Simple equations Solve system of equations: 5x+3y=5 5x+7y=25
8. One hectare How many square meters are one hectare?
9. Circle simple Circumference of a circle is 6.28. What is the area of the circle?
10. Perimeter of square The square has a circumference 17cm. What is its area?
11. The volume The volume of a solid cylinder is 260 cm3 the cylinder is melt down into a cuboid, whose base is a square of 5cm, calculate the height of the cuboid and the surface area of the cuboid
12. Cube walls Find the volume and the surface area of the cube if the area of one of its walls is 40 cm2.
13. Velocipedes In the 19th century, bicycles did not have a chain drive, and the pedals were connected directly to the wheel axis. This wheel diameter gradually increased until the so-called high bicycles (velocipedes) with a front wheel diameter of up to 1.5 meters, whi
14. The number The number of 1 cm cubes required to make 4 cm cube is?
15. Car crash After a traffic accident, police measured 1.16 permille of alcohol in the driver's blood. What amount of alcohol did the driver have in the blood when about 5 kg of blood circulates in the human body?
16. Metal rails Dad needs to improve the edges of the wooden boxes - to be reinforced with metal rails. How many cms of rails will he need if the box has the shape of a prism with the length of the edges 70cm 70cm and 120cm?
17. Water flow 2 How many litres of water will flow in 7 minutes from a cylindrical pipe 1 cm in diameter, if the water flows at a speed of 30 km per hour
18. Surface area 6 Find the surface area of a prism whose bases are right triangles with sides of length 3, 4, and 5 inches and a height of 8 inches. Include a sketch
19. Dropped sheets Three consecutive sheets dropped from the book. The sum of the numbers on the pages of the dropped sheets is 273. What number has the last page of the dropped sheets?
20. Number with ones The first digit of the number is 1, if we move this digit to the end we get a 3 times higher number, which is the number?

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