Math practice for 13 year olds - page 381 of 422
Number of problems found: 8427
- Calcium and citality
The daily dose of calcium was obtained using 0.75 liters of milk and 60 grams of cheese. a/ In the morning, I drank half a liter of milk. How much cheese must I eat to consume a daily dose of calcium? b/ I ate 50 grams of cheese. How much milk must I drin - Tetrahedral pyramid
Calculate the volume and surface area of a regular tetrahedral pyramid; its height is $b cm, and the length of the edges of the base is 6 cm. - Four-digit number
Find a four-digit number, which quadrupled written backward is the same number. - Juice box 2
The box with juice has the shape of a cuboid. Internal dimensions are 15 cm, 20 cm, and 32 cm. Suppose the box stays at the smallest base juice level and reaches 4 cm below the upper base. How much internal volume of the box fills juice? How many cm below - Three co-owners
The three co-owners of the building company have earnings from a contract portioned in the ratio of 3:6:7. Each of them received the amount in the whole USD. One of them, on contract, earned 86450 USD. What were the total earnings for this order? - angles in quadrilateral
What size have angles in quadrilateral (4-gon) if they are in a ratio of 8:9:10:13? - 10 pieces
How to divide the circle into ten parts (geometrically)? - The city
In the city, 2/4 of women are married to 3/4 of men. What percentage of townspeople is single (not married)? - Truck
In 7 hours, we started from the town Krnov truck at a speed of 40 km/h. Passenger cars started against it in 8 hours 30 minutes from the city of Jihlava at a speed of 70 km/h. The distance between these two cities is 225 km. At what time and distance do t - Salt
One ton of seawater contains 25 kg of salt. How many tons of seawater must be evaporated to obtain 2 q of salt? - Sisters
Sisters Janka and Danka have 220 CZK saved together. She wants to take a fifth of her savings and Danka's quarter on a trip to Janka. Then, they will have 50 CZK on the trip. How much money did Janka and Danka have? - Double-track
On double-track express met with a freight train. Express travel at a speed of 72 km/h, and a freight train at a speed of 36 km/h. After what period will it be from 9 km apart? - School year
At the end of the school year, 20% of the 250 children who attended school were awarded. 18% of boys and 23% of girls received awards. Find the number of boys and girls who attend school. - 4 pipes
The tank flows out by four pipes in 6 hours 120 hl water. How much water flows out of 5 pipes of the same diameter in 14 hours? - Ladder 2
The ladder 9.8 meters long is positioned in the well such that its lower end is distanced from the wall of the well 1.2 m. The upper part of the ladder is supported on the upper edge of the well. How high is the well? - Metal alloy
What is the metal ratio in the alloy in the 50 tonnes of steel to 30 kg nickel? - Pyramid a+h Calculate the pyramid's volume and surface area with the edge and height a = 26 cm. h = 3 dm.
- The farmer field
The field has a parallelogram shape with dimensions side a = 67 m and height 387 m. Two and two sides are at an angle 67°. Calculate the acreage of the field in hectares. - Parachutists
During freefall, parachutists were first held in groups of 4, then 6, then 9, 12, and finally 18 members. If each group must all be involved, how many parachutists must jump at least? - Diamond
The side length of the diamond is 35 cm, and the length of the diagonal is 56 cm. Calculate the height and length of the second diagonal.
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