# Units - examples - page 53

1. Average height
In a class are 34 students. The average height of students is 165 cm. What will be the average height of students in the classroom when two pupils tall 176 cm and 170 cm moved from this school/class?
2. Mr. John
Mr. John wants to buy winter apples Spartan. There are two ways to buy: 1) buy apples at the marketplace, where 1 kg costs 15 CZK. 2) Bring the car to the agricultural farm, where the apples are sold after 9 CZK per kilogram. However, he must pay CZK 150.
3. Painting
To paint the pool with dimensions: 2 meters depth, 3m x 4m we bought paint to 50 meters square. How many "paint" will be a waste?
4. Welders
Welder do the job for six hours, the second one for 8 hours. How long do the job third welder if all together can do job in 2 hours?
5. Sputnik
The first Earth satellite was flying at speed 8000 m/s. At that rate he circled the earth in 82 minutes. Jet flies at an average speed 800 km/h. How long would it take circle the earth round?
6. The creek
Workers cleaned the creek within 3 days. The first day cleanse one-fifth the length of the creek, the next day 40% of the length of the stream and the third day 8 km length of the creek. How long is a creek?
7. Juice box 2
Box with juice has the shape of a cuboid. Internal dimensions are 15 cm, 20 cm and 32 cm. If the box stay at the smallest base juice level reaches 4 cm below the upper base. How much internal volume of the box fills juice? How many cm below the top of the
8. Digits of age
The product of the digits of Andrew age as 6 years ago and not equal to 0. Andrew age is also the smallest possible age with this two conditions. After how many years will be the product of the digits of Andrew age again the same as today?
9. James
James paints a fence. If every day instead of 14 planks painted 16 would be done on one day earlier. How many of planks has a fence altogether?
10. Rotary cylinder 2
Base circumference of the rotary cylinder has same length as its height. What is the surface area of cylinder if its volume is 250 dm3?
11. Fence
How many meters of fencing it is required to purchase if our garden is rectangular measuring 20 m and 180 dm.
12. Saw
Blade circular saw with a diameter 42 cm turns 825 times per minute. Expresses his cutting speed in meters per minute.
13. Cash back
After a trip 24 students have left more than 650 but less than 690 CZK (Kc). How much each student receives return when the amount is divisible by the number of pupils?
14. Water well
Drilled well has a depth 20 meters and 0.1 meters radius. How many liters of water can fit into the well?
15. Cleaners
Milan would clean up the room for 2.5 hours, Eric would take 10 hours. How long they swept the room together?
16. Trapezium
The area of trapezium is 35cm2 find its altitude if the bases are 6cm and 8cm.
17. Copper plate
Calculate the thickness of the copper plate with a density 8.7 g/cm³ measuring 1.5 meters and 80 cm and its weight is 3.65 kg
18. Prism
The base of a perpendicular triangular prism is a right triangle with legs 4.5 cm and 6 cm long. What is the surface of the prism, if its volume is 54 cubic centimeters?
19. Street
Straight streets is long x = 1425 meters. At the beginning and at the end of the street are poles. The poles are spaced 25 m. How many poles are on the street?
20. Harvester
Harvester has cutting width 4 m and harvested grain in the field, which is 87 meters wide. Harvester moves along the length of the field for six minutes, going back (without cutting) it takes half the time. Each turn at the end field take one minute. How m

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