Math practice for 13 year olds - page 241 of 428
Number of problems found: 8556
- Probability - coloured balls
We have ten white, ten red, and ten blue balls in our pockets. We selected five white, two red, and three blue balls. What is the probability that we will pick a white ball in the next move? - Map distance ratio
On a map with a scale of 1:500,000, the aerial distance is equal to 12 cm. The distance by rail is equal to 100 km. The road distance is 92 km. Express the air, rail, and road distance in a step-by-step ratio. - Tourist
A tourist walked an average speed of 3.5 km/h route in 6 hours. Calculate how many hours he would have passed at an average speed of 5.5 km/h. - Castle model
The castle model has a cone-shaped roof. The cone side is 45 cm long, and the base radius is 27 cm. a) What is the roof volume? b) How much dm² of wallpaper is used to glue the roof, i.e., the cone shell? c) What is the roof's weight if it is made of wood - Volleyball Tournament Ranking
Classes 1B, 2A, and 3C, participated in the volleyball tournament. How many ways could they take first, second, or third place? What is the probability that 1B will end before 2A class? - Two Trains Meeting Time Distance
A train travels from station A to station B at a speed of 90 km/h. Another train travels from station B to station A at a speed of 45 km/h. The distance between the stations is 60 km. They leave at the same time. How long will they meet and at which kilom - Barrel Water Weight Empty
The barrel of water weighed 64 kg. When We poured 28% of the water from it on the first day and a third of the rest on the second day, it weighed 38 kg. Calculate the empty barrel's weight and the water's initial weight. - Ice Cream Cone Volume Melt
The ice cream sundae glass has a cone shape. Its height without legs is 9 cm, and its radius is 5 cm. Šimon bought eight scoops of ice cream, which all melted in the sun. One scoop of ice cream has a volume of 32 cm³. How many cm³ of melted ice cream will - Diamond and diagonals
A diamond has diagonals f = 8 cm and g = 6 cm long. How long is this diamond perimeter? (Calculate it!) - Line Segment Division Ratio
Divide a line 9 cm long in a ratio of 3:5:4 - Down syndrome
Down syndrome is one of the serious diseases caused by a gene mutation. Down syndrome occurs in approximately every 550-born child. Express the incidence of Down's syndrome in newborns at per mille. - Masquerade ball
Marie wants to make a cone-shaped witch's hat for a masquerade ball. How much material will it need if it counts on an annular rim with diameters of 28cm and 44cm? The hat side length is 30cm. Add 5% of the material to the bust. Round to cm². - Probability of Digit Sum
There are chips in the bag with numbers from 1 to 25. What is the probability of choosing a number with a digit sum of 6? - Trip money puzzle
Vášek went on a trip, and since he had little money, he lent Lukáš the same amount he had. When he spent 40 crowns, he again borrowed from Adam the same amount as he had in his wallet. When he spent 40 crowns again, he was completely penniless. What amoun - Dog price
Tereza agreed to get a dog and 6000 crowns a year for help in a dachshund breeding station. After eight months, she had to finish work and got a dog and 2000 crowns. What price does a dog have? - Four-Digit PIN Codes
How many 4-digit numeric pin codes can be created so that not all four digits are identical? - Prism 4 sides
The prism has a square base with a side length of 3 cm. The diagonal of the sidewall of the prism (BG) is 5 cm. Calculate the surface of this prism in cm square and the volume in liters. - Weight of Gold Pyramid
The teacher cast the gold in the shape of a regular triangular pyramid with a base edge length of 12 cm and a height of 8 cm. The density of gold is 19,320 kg/m³. What is the weight of the casting? - Castle tower
The castle tower has a cone-shaped roof with a diameter of 10 meters and a height of 8 meters. If we add one-third to the overlap, calculate how many m² of coverage is needed to cover it. - Cube into cylinder
If we dip a wooden cube into a barrel with a 40cm radius, the water will rise 10 cm. What is the size of the cube edge?
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