# Examples for 7th grade (seventh) - page 5

1. Greenhouses Two workers would make installation of greenhouses for 54 hours. For how many hours does the installation 9 workers?
2. 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?
3. 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.
4. Motion Cyclist started at 9:00 from point S to point T. After 10 minutes, followed him at the same speed the second cyclist. Walker, which went from T to S, started at 9:35. After 71 minutes he met the first cyclist and after next 8 minutes the second cyclist. Di
5. Expansion If one side of the rectangle is larger 4-times and second 2-times, what percentage increases the area of rectangle?
6. Cu thief The thief stole 122 meters copper wire with cross-section area of 95 mm2. Calculate how much money gets in the scrap redemption, if redeemed copper for 5.5 eur/kg? The density of copper is 8.96 t/m3.
7. Earth parallel Earth's radius is 6370 km long. Calculate the length parallel of latitude 50°.
8. Arc Circle arc corresponding to angle is 32° is 28 dm long. What is the length of the entire circle?
9. Similarity Are two right triangles similar to each other if the first one has a acute angle 70° and second one has acute angle 20°?
10. Birthdate Jane on birthday brought 30 lollipops and 24 chewing gum for their friends. How many friends has, if everyone receives the same number of lollipops and chewing gums? How much chewing gum and lollipops got any friend?
11. Pedestrian up-down hill Pedestrian goes for a walk first at plane at 4 km/h, then uphill 3 km/h. Then it is in the middle of the route, turns back and goes downhill at speed 6 km/h. Total walk was 6 hours. How many kilometers went pedestrian?
12. Kites Boys run kite on a cable of 68 meters long. What is the kite altitude, if the angle from the horizontal plane is 72°?
13. Reciprocal For given real numbers, calculate reciprocal number. Ladder 8 m long is leaning against the wall. Its foot is 1 m away from the wall. In which height ladder touches the wall?
15. Bureau of Labor Bureau of Labor is a state institution that provides mike and the rest for their so-called clients. The mission of the Bureau of Labor is spend taxpayer money to provide relaxation and benefits to those who do not want to work. Popularly speaking sense the
16. VAT John paid 100 Euros in store for purchase. Calculate value added tax (VAT), which paid in purchase, if the VAT rate is 20%.
17. Reconstruction of the corridor Calculate how many minutes will be reduced to travel 187 km long railway corridor, where the maximum speed increases from 120 km/h to 160 km/h. Calculate how many minutes will shorten travel time, if we consider that the train must stop at 6 stations, eac
18. Trolleybus Trolleybus line No. 206 measured 24 km. If the trolleybus goes faster by 5 km/h, the way there and back would is shorter by 33 minutes. Calculate the trolleybus speed and how much time it takes a return trip.
19. Air mass What is the weight of the air in a classroom with dimensions 10 m × 10 m × 2.7 m ? The air density is 1.293 kg/m3.
20. Triangle Can be rectangular triangle equilateral?

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