# Examples for 7th grade (seventh) - page 31

1. Clock How long is trajectory of second hand of hours for day, if is 15 mm long?
2. Wheel How many times turns the wheel of a passenger car in one second if car run at speed 100 km/h. Wheel diameter is d = 62 cm.
3. The carpet How many meters of carpet 90 cm wide need to cover floor room which has a rectangular shape with a lengths 4.8 m and 2.4 m if the number of pieces on the carpet is needed to be lowest?
4. Disjoint How many elements have union and intersection of two disjoint sets when the first have 1 and secodn 8 elements.
5. Quiz Tested student answered correctly on a 4/ 8 questions. Wrong answers was 16. How many questions answered?
6. Salary increase Ms. Merry salary increased by 15% and that was 83e. What should pay before the increase?
7. The book The book has 280 pages. Each side is a rectangle with sides 15 cm and 22 cm. a) how many leaves has the book? b) at least how many square meters of paper should be used to production this book?
8. Lunch Jane eats whole lunch for the 30 minutes. Which part of the lunch is eaten in 180 seconds?
9. Wheels Small tractor wheel with a diameter of 60 cm must be rotated 8 times to overcome some pathway. How many times must turn the big tractor wheel with a radius 60 cm to overcome the same distance?
10. Five tractors Five tractors plow field in 4.8 hours. How long plow this field if after 1.5 hours of work two tractors went to a different field?
11. Barrel 2 Empty barrel weighs 7 kg. When it filled with water up to 45% height, weighs 60 kg. How heavy is barrel full of water?
12. Apples and pears Mom divided 24 apples and 15 pears to children. Each child received the same number of apples and pears - same number as his siblings. How many apples (j=?) and pears (h=?) received each child?
13. Tiles How many 46 cm square tiles will cover a floor 22.08 m by 8.74 m?
14. Brackets Place one pair of brackets in expression 20-16 + 10 - 4 - 2 so that the result will be 0.
15. Motor oil 30 liters of oil cost 28.80 Euros. How much cost a liter?
16. Round table tablecloth Round table has area 50.24 dm2. Calculate the diameter of the circular tablecloth, if it is extend beyond the edge of the table by 30 cm.
17. Every day 7 pages Adelka reads the book every day 7 pages. When she reads one more page a day she will read it three days earlier. How long will Adelka read a book? How much does a book of pages have?
18. Water in aquarium The aquarium cuboid shape with a length of 25 cm and a width of 30 cm is 9 liters of water. Calculate the areas which are wetted with water.
19. RT 10 Area of right triangle is 84 cm2 and one of its cathethus is a=10 cm. Calculate perimeter of the triangle ABC.
20. Silo Outer perimeter of silo is 32 m. Concrete wall is 35 cm thick. What is diameter and area of inside floor of silo?

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