Math practice for 13 year olds - page 311 of 434
Number of problems found: 8665
- Square prism
Calculate the volume of a square prism of high 2 dm wherein the base is: Rectangle with sides of 17 cm and 1.3 dm - Sea water
One tonne of seawater contains 25 kg of salt. How many tonnes of seawater needs to be evaporated to obtain 1 tonne of salt? - Flowerbed
The flowerbed has a length of 3500mm and a width of 1400mm. How much foil is needed to cover the flowerbed? How many m² of foil was consumed for its production (add 10% of the material to the joint and waste)? How many liters of air is inside the enclosur - Mr and Mrs
Mr. Calda and Mrs. Cald have a total of 139 years. How many years have when we known that Mr. Calda is nine years older than Mrs. Cald? - The tram
The tram is moving with acceleration a = 0.3m/s2. How long will it pass the first meter of the track? How long does it take 10 meters? What is its speed at the end of the 10-meter track? - Pumps 4912
A pool with one pump fills in 14 hours and the other in 15 hours. How long will the pool fill when both pumps are used? - Driver
The driver of the supply car reckoned that at the average speed of 72 km/h arrived at the warehouse for 1 1/4 hours. After 30 km, however, he unintentionally drove to the gas station and had ten minutes delay. At what average speed would you have to go th
- Trapezoid 4908
Trapezoid ABCD with bases AB = a, CD = c has height v. The point S is the center of the arm BC. Prove that the area of the ASD triangle is equal to half the area of the ABCD trapezoid. - Immediately 4906
It is Monday at 10 a.m. Luboš has returned from the doctor, who prescribed him tablets: he will take the first one immediately, the next two days he will take them after six hours, and the rest after eight hours. When will Luboš collect all the tablets if - Deviation 4905
The flower bed has the shape of a regular 4-sided pyramid. The edge of the lower plinth is 10 m, and the upper plinth is 9 m. The deviation of the side wall from the base is 45 degrees. How many plantings should be purchased if 90 are needed to plant 1 sq - Painting
To paint the pool with dimensions: 2 meters depth, 3m x 4m we bought paint to 50 meters square. How much "paint" will be wasted? - Increased 4898
The price of flour increased three times in a row by 10% each time. The shop then reduced it by 30%. Now the price of flour is 5.60 CZK. What was the original price? - Right triangle trigonometrics
Calculate the size of the remaining sides and angles of a right triangle ABC if it is given: b = 10 cm; c = 20 cm; angle alpha = 60°, and the angle beta = 30° (use the Pythagorean theorem and functions sine, cosine, tangent, cotangent) - Forces on earth directions
A force of 60 N [North] and 80 N [East] is exerted on an object weight of 10 kg. What is the acceleration of the object? - Volume increase How much percent will increase in the pool 50 m, width 15m if the level rises from 1m to 150cm?
- Hydrostatic force
What is the hydrostatic force applied to an area of 30 cm² in the water at a depth of 20 m? (Water density is 1000 kg/m3) - Sales of products
For 80 pieces of two quality products, the total sales are 175 Eur. Suppose the first quality product was sold for n EUR per piece (n natural number) and the second quality product after 2 EUR per piece. How many pieces of the first quality were sold? - Sphere radius
The surface of the sphere is 60 cm square. Calculate its radius; result round to tenth of cm. - Championships 4886
The pool had to be filled before the World Championships. The first pump would fill in 12 hours, the second in 15 hours, and if all three pumps were started simultaneously, they would fill the pool in 4 hours. How long would the pool be filled with only t - Two-digit 4883 Dad had 33 bills. One hundred crowns, two hundred and five hundred. A two-digit number gave the number of each species. How many did he have if he had a total of 9100 CZK?
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