# Examples for 7th grade (seventh) - page 11

1. Wire D Wire length 1 m is bent so that it forms a semicircle circuit (including the diameter). Determine the radius of the semicircle.
2. Cyclists Cyclist who rides at an average speed 16 km/h travels trip distance 10 min before the cyclist who rides at an average speed 11 km/h. What is the length of this cyclist trip(distance in km)?
3. Magnification of the square If we increase the square side, increase the content of the 80 %. About what percentage was increased his sides?
4. Arm Calculate the length of the arm r of isosceles triangle ABC, with base |AB| = 14 cm and a height v=18 cm.
5. Tanker An oil tanker can be emptied by the first pump in 4.9 hours. Second pump can empty an tanker in 8 hours. If the first pump started at 4:00 and second 1.4 hour later, at what time will the tanker be empty?
6. Election mathematics In elections, 12 political parties received this shares of voters: party A 56.2 %party B 8.5 %party C 8.2 %party D 6.2 %party E 6.1 %party F 5.5 %party G 3.2 %party H 2.1 %party I 2 %party J 1 %party K 1 % Calculate what the shares acquired in the parlia
7. Cone and the ratio Rotational cone has a height 23 cm and the ratio of the base surface to lateral surface is 7: 9. Calculate a surface of the base and the lateral surface.
8. Sea on the Moon Assume that the Moon has sea, the same composition as on the Earth (has same density of salt water). Calculate dive of boat floating in the sea on the Moon, when on Earth has dive 3.6 m. Consider that the Moon has 6.5-times smaller gravitational accelerati
9. Dog II Journey from a rangers' home to the town is 6 km. Mr. ranger started from his home and went 3 km per hour. His women came from the town and also went 3 km per hour. With ranger started dog and runs in 12 km in 1 hour. The dog went to ranger's women then.
10. Milk package Milk is sold in a box with dimensions of 9.5 cm; 16.5 cm and 6.5 cm. Determine the maximum amount of milk that can fit into a box. Coating thickness is negligible.
11. Triangle angles The angles α, β, γ in triangle ABC are in the ratio 6:2:6. Calculate size of angles.
12. Sector The perimeter of a circular sector with an angle 1.8 rad is 64 cm. Determine the radius of the circle from which the sector comes.
13. EQL triangle Calculate inradius and circumradius of equilateral triangle with side a=77 cm.
14. Cube wall Surface of first cube wall his 225 mm2. Second cube area is 60% of the surface of the first cube. Determine the length of the edge of the second cube (x).
15. Mailbox Mailbox is opening at regular intervals 3 times a day. The first time is opened at 8:00 and the last at 19:00. Calculate hours when mailbox is opened during day.
16. Parallelogram Calculate the area and perimeter of a parallelogram whose two sides are long a=24 cm b=22 cm and height ha = 6 cm long.
17. Equilateral triangle Calculate the side of an equilateral triangle, if its area is 892 mm2.
18. Tractors Six tractors plowing the field for 8 days. After two days, two tractors broke down. How many days were prolonged work in the field?
19. XY triangle Determine area of triangle given by line 7x+8y-69=0 and coordinate axes x and y.
20. Three workers Three workers A, B, C have to work on a specific task. Workers A and B completed whole task in 14 days, B together with C for 23 days, A together with C for 13 days. How long it would take to complete the task every one of them alone? How long it would.

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