# Units - examples - page 102

1. Height as diameter of base
The rotary cylinder has a height equal to the base diameter and the surface of 471 cm2. Calculate the volume of a cylinder.
2. Circular arc
Calculate the length of the circular arc if the diameter d = 20cm and the angle alpha = 142 °
3. Highway tunnel
The highway tunnel was built from two ends in the north-south direction. The average daily performance of the "northern party" rasters was higher than the average daily power of the "southern party" of the rasters. After 55 business days, both parties met.
4. Map scale
The rectangular plot has in a scale of 1: 10000 area 3 cm2 on the map. What content does this plot have on a 1:5000 scale map?
5. Irrigation sprinkler
The irrigation sprinkler can twist with an angle of 320° and has a reach of 12 meters. Which area can irrigate?
6. Water current speed.
Two cities along the river are 100 km apart. The powerboat downstream runs for 4 hours, upstream for 10 hours. Determines the river's current speed.
7. Filament of bulb
The filament of bulb has a 1 ohm resistivity and is connected to a voltage 220 V. How much electric charge will pass through the fiber when the electric current passes for 10 seconds?
8. Bricklayers
Seven bricklayers will build the house in 630 days. How many bricklayers do we need to take after 150 days to complete the building for (additional) 336 days?
9. Tropical, mild and arctic
How many percents of the Earth's surface lies in the tropical, mild and arctic range? The border between the ranges is the parallel 23°27 'and 66°33'.
10. Acid evaporation
How many kilograms of water do we have to evaporate from 100 kg of 32% acid to make it 80% concentration?
11. Edges or sides
Calculate the cube volume, if the sum of the lengths of all sides is 276 cm.
12. Sum of inner angles
Prove that the sum of all inner angles of any convex n-angle equals (n-2) . 180 degrees.
13. Borrowing
I borrow 25,000 to 6.9% p.a.. I pay 500 per month. How much will I pay and for how long?
14. Each chair
Each chair costs twice less than two tables. One table costs 720 Czech crowns. How many crowns are the table and 4 chairs?
15. Cylinder-shaped vase
If the cylinder-shaped vase is filled with water up to 35 cm, it contains 1 liter of water. How much water will it contain if it is filled to a height of 45cm?
16. Lunch
Seven classmates go every day for lunch. If they always come to the front in a different order, will be enough school year to take of all the possibilities?
17. Running
Joanne ran 8 1/2 Kyleigh 1 2/3 and John 6 3/4 miles in one day. How many miles did the girls run in 3 days?
18. Water reservoir
One drain hole emptied the water from the tank for 20 hours, with the second drain for 30 hours. How long will the water drain from this tank if we open two drains simultaneously?
19. Michal
Michal has 2.90 per hour. How much does he earn during the week of the summer job?
20. Father 7
Father is 6 times older than his son. After 4 years, the father will only be 4 times older. What are their present ages?

Do you have an interesting mathematical example that you can't solve it? Enter it, and we can try to solve it.

To this e-mail address, we will reply solution; solved examples are also published here. Please enter e-mail correctly and check whether you don't have a full mailbox.