Math practice for 13 year olds - page 76 of 428

Number of problems found: 8558

Boat water speed
The water in the river has a speed of 4.8 km/h relative to the bank. A boat in still water has a speed of 12.6 km/h. a) What is the boat's speed relative to the shore if it is sailing downstream and upstream of the river? b) What path will the boat travel
Triangle angle determination
In one triangle, one angle is 43°, and the second is 15° less than the third. Determine the unknown angles of the triangle.
Cannon sound speed
A cannon fired at a distance of 2720 m from the observer. The sound of the shot was heard by the observer 8 seconds after the flash. Calculate the speed of sound propagation in the air if we assume that the observer saw the flash at the same time as the s
Egypt trip discount
A trip to Egypt was discounted by one-third of the price at the last minute. The discount was 5760 CZK. What was the original price of the tour?
School trip graders
Sixth, seventh, and eighth graders took part in the school trip. Sixth graders were 5 more than seventh graders, and eighth graders were 3 less than sixth graders. How many sixth graders were on the trip if there were 73 students in total?
Cone surface volume
The cone's surface is 75.36 cm, and the radius is 3 cm. Calculate the volume of the cone.
Car average speed
A car drives for an hour on the highway at a speed of 100 km/h, then for half an hour at a speed of 80 km/h, and for another half hour in the field at a speed of 20 km/h. What track did he run together? What is the average speed of the car?
Dye water proportion
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.
Volleyball rack capacity
Calculate how many volleyballs with a circumference of 65 cm fit into a cube-shaped rack whose edge is 100 cm long.
Fraction addition division
Add one-third to five-eighths and divide the result by the sum of the numbers five-quarters and two-thirds.
Number double reduced
It is necessary to determine the number whose double is reduced by 15 equals the number 5.
Puzzle wood density
The picture puzzle made of wooden cubes weighs 0.792 kg. One cube has an edge length of 4 cm and a weight of 33 grams. Find out how many cubes make up a puzzle and calculate the wood density in kg/m³.
Gunpowder component mixture
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.?
Natural number sum
Calculate the sum of the squares of single-digit natural numbers less than 6
Wreath cream price
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?
Three ratios
Calculate x in terms of: x:7=6:4 1/2:x=5:3/4 4:3=8:x
Pupil number decrease
Over five years, the number of pupils in the school decreased from 455 to 335. By what percentage did the number of pupils decrease?
Dress double discount
Dresses that initially cost 100 € after a double discount of 10% subsequently increased in price by 20%. How much did they cost?
Spherical layer volume
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?
Class boy girl
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?

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