Maths practice for 14 year olds - page 57 of 379
Number of problems found: 7567
- Proportion 81558
Pour 9 dl of dye into 100 liters of water. What will be the proportion of dye in the resulting mixture? Express as a percentage.
- Circumference 81557
Calculate how many volleyballs with a circumference of 65 cm fit into a cube-shaped rack whose edge is 100 cm long.
- Components 81552
Gunpowder is made from a mixture of coal, sulfur, and lignite, with 4 times more lignite than sulfur and 3 times more sulfur than coal. Calculate how many kilograms of individual components are needed to produce 240 kg of gunpowder.?
- Wreaths 81547
Eva paid €8.4 for three wreaths and five creams. Jana paid €15.6 for 9 wreaths and 7 creams. How many crowns will Jan pay for one wreath and one cream?
- Quadrilateral 81544
In the general quadrilateral ABCD, angle β is 9° greater than angle α, angle γ is 24° greater than angle α, and angle δ is 50° greater than angle β. Determine the sizes of individual angles.
- Three ratios
Calculate x in terms of: x:7=6:4 1/2:x=5:3/4 4:3=8:x
- Percentage 81539
Over five years, the number of pupils in the school decreased from 455 to 335. By what percentage did the number of pupils decrease?
- Subsequently 81532
Dresses that initially cost 100 € after a double discount of 10% subsequently increased in price by 20%. How much did they cost?
- Spherical 81527
Sketch a spherical layer formed from a sphere with a radius of r= 8.5cm, given: v=1.5cm, r1=7.7cm, r2=6.8cm. What is its volume?
- Children 81526
There are 32 children in the class. If there were three more boys and one less girl, there would be an equal number of girls and boys in the class. How many boys are there in the class?
- Savings 81523
The savings of Vlad and Peter are in the ratio of 15:8, and the savings of Peter and Juraj are in the ratio of 2:1. What is the ratio of the savings of Vlad, Petr, and Juraj?
- Glasses 81522
5 out of 32 plates and 2 out of 20 glasses were broken at the party. What is the ratio of plates to glasses now?
- Together 81521
Pavel and Vojta were planting trees at the forestry brigade. Pavel planted two more trees than Vojta in a six-hour shift. Together, they planted 156 saplings in three such shifts. How many saplings did Pavel and Vojta plant during the brigade?
- Cylinder-shaped part
A truncated cone-shaped part with base radii of 4 cm and 22 cm is to be recast into a cylinder-shaped part of the same height as the original part. What base radius will the new part have?
- Weighs 81511
2 hens weigh 1kg more than a goose. 3 hens weigh 1kg more than 2 geese. How much do one hen and one goose weigh? When every goose weighs the same, and every hen weighs the same.
- Resistor 81502
How big a series resistor do we need to connect to the LED if a voltage drop of 3.2 V is to be created on it and a current of 16 mA flows through the diode? We want to connect the diode to a voltage of 5V.
- Selection 4
Selection triangle, which is similar to the given triangle RTG. ∆ RTG, r= 24 dm, t = 28 dm, g= 30 dm. ∆ SHV= 6 dm, h= 7.5 dm, v= 7 dm ∆ VSH= v= 7 dm, s= 6 dm, h= 7.5 dm ∆ HVS= h= 7.5 dm, v= 7 dm, s = 6 dm. ∆ VHS= v= 7 dm, h = 7.5 dm, s= 6 dm. ∆ HSV= h= 7.
- Horsepower 81496
The electric motor has an efficiency of 80% (power and input ratio). What is the power input of this motor if its power is 5 horsepower (HP)? Enter the result in kilowatts (kW) and round to one decimal place (1 HP = 3/4 kW).
- Three-day trip
George went on a moped for a three-day trip. He drove 90 km on the first day, 30 km on the second day, and 60 km on the third day. He always drove at the same average speed and always the whole number of hours. Calculate the average speed if George drove
- Increased 81490
Suzan managed to get 40 points out of a possible 60 from the last paper. Her average number of points from the tests increased from 27 to 28 points. How many points should she have written if she wanted her overall average to rise to 29 points?
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