# Examples for 7th grade (seventh) - page 4

1. Time
Write time in minutes rounded to one decimal place: 5 h 28 m 26 s.
2. Gutter
How much metal is needed for production 46 pieces of gutter pipes with the diameter 12 cm and length of 4 m? The plate bends add 2% of the material.
3. IS trapezoid
Calculate the length of diagonal u and height v of isosceles trapezoid ABCD, whose bases have lengths a = |AB| = 37 cm, c = |CD| = 29 cm and legs b = d = |BC| = |AD| = 28 cm.
4. Railways
Railways climb 7.4 ‰. Calculate the height difference between two points on the railway distant 3539 meters.
5. Water
Mix 68 l of water with temperature of 87 °C, 17 l warm of 42 °C and 55 l water of 50 °C. What is the temperature of the mixed water immediately after mixing?
6. Theater
The theater has in each row with 19 seats. Ticket to the first 10 rows is for 30 USD. In next rows is for 15 USD. The theater was completely sold out. Revenue was 12255 USD. How many rows are in the theater?
7. Right triangle
Legs of right are in ratio a:b = 6:8. Hypotenuse has a length of 61 cm. Calculate the perimeter and area of the triangle.
8. Climb in percentage
The height difference between points A and B is 475 m. Calculate the percentage of route climbing if the horizontal distance places A, B is 7.4 km.
9. Present
Gift box has rectangular shape with dimensions of 8×8×3 cm. Miloslav wants to cover with square paper with sides of 18 cm. How much paper left him?
10. Sea water
Seawater contains about 4.3% salt. How many dm3 of distilled water we must pour into 5 dm3 of sea water to get water with 1.8% salt?
11. Pediatrician
Pediatrician this month of 19 working days takes 3 days holidays. What is the probability that on Monday will be at work?
12. Wage
Increasing the minimum wage while maintaining the other parameters of the system, unemployment will be:
13. Camp
In the camp are children. 1/2 went on a trip, 1/4 went to bathe and 38 children remained in the room. How many children are in camp?
14. Barrel of oil
Barrel of oil weighs 283 kg. When it mold 26% oil, weighed 216 kg. What is the mass of the empty barrel?
15. Car
Car goes from point A to point B at speed 86 km/h and back 53 km/h. If they goes there and back at speed 67 km/h trip would take 10 minutes shorter. What is distance between points A and B?
16. Tare
Gross weight of shipment is 5188 kg and its tare is 5.6%. Calculate the net weight of the shipment.
17. Maximum area of rhombus
Calculate the interior angles at which equilateral rhombus has maximum area.
18. Gear
Two gears, fit into each other, has transfer 2:3. Centres of gears are spaced 82 cm. What are the radii of the gears?
19. Greenhouses
Two workers would make installation of greenhouses for 54 hours. For how many hours does the installation 9 workers?
20. Cone
Circular cone of height 15 cm and volume 5699 cm3 is at one-third of the height (measured from the bottom) cut by a plane parallel to the base. Calculate the radius and circumference of the circular cut.

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