Maths practice for 14 year olds - page 319 of 362
Number of problems found: 7226
- Tea blend
Tea blends are made from two kinds of tea. In standard tea, the mixture is two teas in a ratio of 1:3, and 40 g costs 42 CZK. In the premium tea mixture, weighing two teas in the 1:1 and 50 grams ratio costs 60 CZK. How much cost 10 grams of a more expens - Average
If the average(arithmetic mean) of three numbers x,y, and z are 50. What is the average of their numbers (3x +10), (3y +10), (3z+10)? - Sphere area
A cube with an edge 1 m long is a circumscribed sphere (vertices of the cube lie on a sphere's surface). Find the surface area of the sphere. - Class pairs
In a class of 34 students, including 14 boys and 20 girls. How many couples (heterosexual, boy-girl) can we create? By what formula? - Family parcels
The father will divide the land so that the older son has three bigger parts than the younger son. Later elder son gave a 2.5 ha field to the younger, and they had both the same. Determine the area of the family parcel. - Digits A, B, C
For the various digits A, B, and C is true: the square root of the BC is equal to the A, and the sum B+C is equal to A. Calculate A + 2B + 3C. (BC is a two-digit number, not a product). - Miraculous tree
The miraculous tree grows so fast that the first day increases its height by half the total height of the second day by the third, the third day by a quarter, etc. How many times will it increase its height after 6 days? - Candies
In the box are 12 candies that look the same. Three are filled with nougat, five with nuts, and four with cream. How many sweets must Ivan choose to satisfy himself by selecting two with the same filling? - Water well
A drilled well has a depth of 20 meters and a radius of 0.1 meters. How many liters of water can fit into the well? - Polygon 42
Which polygon has 42 more diagonals than sides? - Clock face
A clock face is drawn on paper. Straight lines connect numbers 10 and 5, and 3 and 8. Calculate the size of their angles. - Circular lawn
Around a circular lawn area is a 2 m wide sidewalk. The outer edge of the sidewalk is a curb whose width is 2 m. The Curbstone and the inner side of the sidewalk together form concentric circles. Calculate the area of the circular lawn, and the result rou - The city 2
Today lives 298000 citizens in the city. How many citizens can we expect in 8 years if their annual increase is 2.4%? - Rhombus base
Calculate the volume and surface area of prisms whose base is a rhombus with diagonals u1 = 17 cm and u2 = 14 cm. The prism height is twice the base edge length. - Tray
If the water level in the tray shaped as a cuboid is 420 liters and the bottom dimensions are 120 cm and 70 cm, what height reaches the water level? - Heating plant
Workers dump imported coke at the heating plant. They used half of the amount on the first day. On the second day, three-quarters of the rest, and on the third day, left 120 tons. How much coke did they dump at the heating plant? - Two cars
From A town started two cars to town B. The first begins at 7:00 at an average speed of 60 km per hour. The second car starts at 10:00 at an average speed of 100 km per hour. The first car will not stay in B, and on the way back, meet the second car halfw - Hockey game
In the hockey game, they scored six goals. The Czechs played against Finland. The Czechs won 4:2. In what order did they fall goals? How many game sequences were possible during the game? - Hollow sphere
The hollow steel sphere floats on the water, plunged into half its volume. Determine the outer radius of the sphere and wall thickness if you know that the weight of the sphere is 0.5 kg and the density of steel is 7850 kg/m³ - Aircrafts
The bomber started at 9:00 from the airport and flew at an average speed of 1850 km/h toward Airfield B, a distance of 3500 km. After evaluating the danger from the airport, B started at 9:45 B towards A fighter at an average speed of 2300 km/h. At what t
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