Math practice for 13 year olds - page 370 of 424
Number of problems found: 8477
- TVs
Production of television sets increased from 3,500 units to 4,200 units. Calculate the percentage of production increase. - Sweets
Three chocolates and seven cakes cost 85 CZK. Two chocolates and six cakes cost 86 CZK. How much are five chocolates and nine cakes? I wonder how to get the result, but only by logic, without using a system of equations. - Cube 5
The surface of the cube is 15.36 dm². How will this cube's surface area change if the edges' length is reduced by 2 cm? - Regular octagon
Draw the regular octagon ABCDEFGH inscribed with the circle k (S; r = 2.5 cm). Select point S' so that |SS'| = 4.5 cm. Draw S (S'): ABCDEFGH - A'B'C'D'E'F'G'H'. - Metal sheet
The box has the shape of a cube with an edge length of 50 cm. How much m² of sheet metal is needed to beat a box if we add 20% on the folds of the lid and walls? - Bricks
Openings in perforated bricks occupy 10%, and brick has dimensions of 30 cm, 15 cm, and 7.5 cm. Calculate a) the weight of a perforated brick if you know that the density of the full brick material is p = 1800 kg/m³ (1.8 kg/dm³) b) the number of perforate - Nectar
Nectar collected by bees contains 70% water. The nectar of the same process produces honey which has 19% water. How many kilograms of nectar do bees need to collect to make 1 kg of honey? - Workers
Ten workers must pave the road for 22 working days. After four days were spent speeding up work, two more workers were added. a) After how many work days do workers complete the paved road? b) How many working days does a total paved road take? - Apprentice
A worker and an apprentice can complete a job together in 6 hours. The worker alone can finish it in 10 hours. How long would the apprentice take alone? - Shepherd
A shepherd has fewer than 500 sheep. When lined up in rows of 2, 3, 4, 5, or 6, there is always one remaining. However, they can be lined up in rows of 7 with none left over. How many sheep does the shepherd have? - Plum
On the platter are plums. How many were there if its have to be able to share equally among 8,10, and 12 children? - Square grid
A square grid consists of a square with sides of a length of 1 cm. Draw at least three patterns, each with an area of 6 cm² and a circumference of 12 cm, and their sides in a square grid. - Christmas Day
In leap years, it was 53 Sundays. On what day of the week fell Christmas Day? - Spirit
From 55% and 80% spirit, we would like to produce 0.2 kg of 60% spirit. How many of them must we use in a solution? - Cuboid box
How much m² paper is needed for the sticking cuboid box of dimensions 50 cm, 40 cm, and 30 cm? To the folds, add one-tenth the area. - Cubes and mouse
The mouse has 27 cubes, which it puts together in a large cube. Then it bit the middle cat on each side and another cat in the middle. The mouse has four children. He then cuts the cube lengthwise. How many cubes and what shape will four mice get? - Container with water
The weight of a container with water is 2.48 kg. Suppose the cast is 75% water, and the container with water weighs 0.98 kg. Determine the weight of the empty container. How much water was originally in the container? - Lift
The largest angle at which the lift rises is 16°31'. Give climb angle in per mille. - Sheep
Shepherd is tending the sheep. Tourists asked him how much they had. The shepherd said, "there are fewer than 500. If I lined up in 4-row, three remain. If in 5-row, four remain. If in 6-row, five remain. But I can form 7-row." How many sheep have a sheph - Whale pressure
The whale, weighing 8 tons, was thrown aground by the sea. The whale is approximately 20 m long and 2 m wide. Estimate the pressure under the belly of a whale. Consider a value of the gravitational acceleration of 10 N/kg.
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