# Examples for 7th grade (seventh)

1. Building At the building, we divided 240 boards into two piles in a 5: 3 ratio. How many were fewer boards in the lower pile?
2. Cubes into cuboid How many 12 centimeter cubes fit into the block (cuboid) with 6dm, 8,4dm and 4,8? Miro stands under a tree and watching its shadow and shadow of the tree. Miro is 180 cm tall and its shade is 1.5 m long. The shadow of the tree is three times as long as Miro's shadow. How tall is the tree in meters?
4. Surface area 6 Find the surface area of a prism whose bases are right triangles with sides of length 3, 4, and 5 inches and a height of 8 inches. Include a sketch
5. Three pumps The water tank is emptied with the first pump in 6 hours, with the second pump in 2 hours. In order to be emptied in 1 hour, all three pumps had to be started at once. How long will take tank be emptied by only the third pump?
6. Three 43 Three brothers inherited a cash amount of 62,000 and they divided it among themselves in the ratio of 5:4:1. How much more is the largest share than the smallest share?
7. Water flow 2 How many litres of water will flow in 7 minutes from a cylindrical pipe 1 cm in diameter, if the water flows at a speed of 30 km per hour
8. Rectangular prism If i have a rectangular prism with a length of 1,000 cm, width of 30 cm and a height of 50 cm, what is the volume?
9. Mysterious number The magician thinks the number: "The mysterious number is first divided by minus five, dividing the result by three, multiplying the number by ten, and dividing the resulting number by minus four. This gives result 5. Can you reveal the mysterious number
10. Thunderstorm The sound travels 1 km in about 3 seconds. How far is the storm if there is a time interval of 8 seconds between lightning and thunder?
11. Seven Seven friends agree to send everyone a holiday card. How many postcards were sent?
12. Report 2 A School reports students to teacher ratio of 6:1. If there are 45 teachers in the School, how many students are there?
13. Simple sequence Continue with this series of numbers: 1792,448, 112, _, _
14. Two discounts The MP4 player cost 960 CZK, the price was twice gradually reduced in the ratio 4: 3: 3/2. How much did the player cost after the second discount?
15. Dinosaurs More than 30 and less than 60 dinosaurs have met at the pond. A quarter of them bathed and 1/7 saws and the rest gripped. How many were at the pond? How many were there?
16. Dropped sheets Three consecutive sheets dropped from the book. The sum of the numbers on the pages of the dropped sheets is 273. What number has the last page of the dropped sheets?
17. Twenty Twenty rabbits are put in 4 cells so that there are different number of rabbits in each cell contains at least 3 rabbits. What is the largest possible number of rabbits in one cell
18. How much How much money will we pay for 20 planks 4m long, 15cm wide and 26mm thick when 1m³ of wood costs 4500kč?
19. Rhombus 29 One of the diagonals of a rhombus is equal to a side of the rhombus. Find the angles of the rhombus.
20. Pool tiles The pool is 25m long, 10m wide and 160cm deep. How many m2 of tiles will be needed on the walls and the pool? How many pieces of tile are needed when 1 tile has a square shape with a 20cm side? How much does it cost when 1m2 of tiles costs 258 Kc?

Do you have an interesting mathematical word problem that you can't solve it? Submit math problem, and we can try to solve it.

We will send a solution to your e-mail address. Solved examples are also published here. Please enter the e-mail correctly and check whether you don't have a full mailbox.

Please do not submit problems from current active competitions such as Mathematical Olympiad, correspondence seminars etc...