# Units - examples - page 29

1. Two diggers
There are two diggers. One digger digs a pit 46 hours second gidding 2 times faster. a) how long took to dig a pit second digger b) how long took dig together
2. Tourist Jirka
Distance between the points A and B is 13.5 km. Jirka went from point A to point B unknown speed and for an unknown period of time. Back to the point A went slower by 3 km/h which means that went 20 minutes more. How long Jirka took the return journey?
3. Bomber
Bomber flies 10 km at 600 km/h. At what horizontal distance from the target, must pilot drop the bomb to hit the target? Don't care about air resistance and consider the gravitational acceleration g=9.81 m/s2.
4. Population
The town has 65,000 inhabitants. 40 years ago there were 157,000. How many people will live in town in 10 years if the average rate in population is as in previous years?
5. Lorry
The lorry was loaded with 18 boxes of 15 kg. How many boxes with weight 18 kg can be loaded, if total load must be same?
6. Divers
20-member group of divers carries the air for 15 hours of diving. 4 members of the expedition sick or wasn't came. How many hours is sufficient air to other divers?
Grandson with grandpa they counted how many years have together. Their product is 365. How many years is the sum of their years.
8. Aquarium II
Calculate how much glass we need to build an aquarium with a rectangular shape with base 70 cm × 70 cm and a height of 70 cm, if the waste is 2%. Aquarium haven't top glass.
9. Cast brass
Brass cast weight was 3.84 kg, it had turned into piston weight 3.491 kg. How many grams of brass was turned off?
10. 30-60-90
The longer leg of a 30°-60°-90° triangle measures 5. What is the length of the shorter leg?
11. Two cars
From the town A to town B started two cars. The first at 7:00 at average speed 60 km per hour, the second at 10:00 at average speed 100 km per hour. The first car will not stay in B, and on the way back meet the second car at half way from A to B. At what.
12. Iron fence
One field of iron fence consists of 20 iron rods with square cross-section of 1.5 cm side and a long 1 meter. How much weight a field if the density of iron is 7800 kg/m3.
13. Racer
The first racer run at a speed 20 m/s and is 750 meters before the finish and ahead 79 meters before second competitor. At what speed must run the second racer to catch first racer at the finish line?
14. Strawberries
Father collects strawberries himself in 4 hours, son in 14 hours. How long will it take them along when dad comes to help son collect strawberries after 3 hours?
15. Granite cube
What is the weight in kg granite cube with an edge of 0.5 m if 1dm3 of granite weight 2600 g?
16. Surface of the cylinder
Calculate the surface area of the cylinder when its volume is 45 l and the perimeter of base is three times of the height.
17. Copper plate
Copper plate length 3.2 m and width 50 cm weighs 55.42 kg. What is the plate thick, if 1 m3 of copper weighs about 8700 kg?
18. Unions
Calculate how much money per year would go to the treasury of unions if 218 thousand employee join unions with an average net salary of 407 euros and if memberhip in union cost 1% of the net monthly salary.
19. Cuboids in cube
How many cuboids with dimensions of 6 cm, 8 cm and 12 cm can fit into a cube with side 96 centimeters?
20. Painter 3
Dad want to paint wall high 250 cm wide and 230 cm with wallpaper. How many meters must buy wallpaper if wallpaper width is 60 cm?

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