Math practice for 13 year olds - page 238 of 415
Number of problems found: 8281
- Concentric circles
There is given a Circle K with a radius r = 8 cm. How large must a radius have a smaller concentric circle that divides the circle K into two parts with the same area? - Assembly parts
Nine machines produce 1,800 parts on nine machines. How many hours will it produce 2 100 parts on seven such machines? - Seven workers
Seven workers clear the glade in 22 hours. How many workers would be needed to complete the task in 8 hours? - Cylinder in a Cube
The cube has an edge length of 5 cm. This cube surrounds a rotating cylinder. Find the surface area of the shell and the volume of the cylinder. - Bed 10
A bed in the shape of two equilateral triangles sharing a common side, with a side length of 2.5 m, is to be planted with seedlings of an ornamental shrub. The gardener recommended leaving 40 cm between individual seedlings and 10 cm from the perimeter ed - 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. - The cone
The cone has a base radius of 12 cm and a height of 20 cm. It was truncated at 6 cm from the base. We created a truncated cone - frustum. Find the radius of the base of the truncated cone. - 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, 2 A, and 3 C, 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 2 A 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 - Candidates
The citizens of Kocúrkovo elected a mayor from two candidates. The winning candidate received 51% of all votes, which was 12 votes more than the defeated candidate received. 75% of all eligible voters came to the vote and all votes were valid. How many ci - 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 28 cm and 44 cm? The hat side length is 30 cm. 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?
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