1. Annulus
The radius of the larger circle is 8cm, the radius of smaller is 5cm. Calculate the contents of the annulus.
2. News
From 28 students buy magazine 10 The economist students, 10 Pravda students and 18 students don't buy any of these magazines. How many students buy both magazines?
3. Stairs
Between adjacent levels are 15 stairs. If step will be 1.2 cm lower there would be 16 stairs. What is the stair height?
4. Nine balls
Imagine that you have exactly the same appearance nine balls of which one has a greater mass than the other. You have isosceles weights. Post a procedure as you would using a weights to discover heavier balls. How many measurements at least you have to do?
5. Roots
Calculate the square root of these numbers:
6. Square room
What is the size of the smallest square room, which can pave with tiles with dimensions 55 cm and 45 cm? How many such tiles is needed?
7. Homework
Mother and Kate together weigh 24.5 kg more than the father. Father weighs 7.6 kg more than mother. Father weight 44.8 kg more than Kate. Determine weights of father mother and Kate.
8. Division
Divide by the number 0.2 is the same as multiply by what number?
9. Shaving
Mathematical problem from Sunday evening. If the beard is growing at 0.52 mm per day and that my length is 16.8 mm, how long I don't shave?
10. Tailor
Tailor has an estimated 11 meters of 80 cm wide fabric. He will shape wholly 7 rectangles measuring 80 x 150 cm and nothing fabric does not remain. How many fabric he have?
11. Cube basics
How long is the edge length of a cube with volume 23 m3?
12. The wall
We have to build a cuboid wall with dimensions base 30 cm and 45 cm and height 3.25 meters. Calculate how many we need bricks if we spend 400 pieces of bricks to 1 m3 of wall?
13. Triangle
For how many integer values of x can 16, 15 and x be the lengths of the sides of triangle?
14. Cuboid - simple
Calculate the surface area and volume of a cuboid if a = 8 cm, b = 14 cm and c = 6 cm.
Car started at 11:40 at speed 54 km/h from A and to B arrived at 12:20. Determine the distance A and B.
16. Decomposition
Make decomposition using prime numbers of number 155. Result write as prime factors (all, even multiple)
17. Rabbits
Michael breeding rabbits. His 7 rabbits will eat 98 feed rations for 7 days. How many equal portions of feed should be eat 5 rabbits in 6 days?
18. Tons of coal
Coal hopper has a capacity of 285 liters. How many tons is it? The bulk density of coal is 916 kg/m3.
19. Cellar
Cellar for storing fruit has a rectangular base with sides 14 m and 7 meters. You should paint sidewall to 2 m. How m2 surface must be painted?
20. Czech crowns
Small Petra save money. Grandfather give her 10 crowns. Petra asked his older sister let her calculate how much he has saved up. Sister told her that he has less than 30 crowns. If the sum is divided by three left one crown. If the sum is divided by the f

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