Math practice for 13 year olds - page 207 of 424
Number of problems found: 8466
- Brother 23201
Karel would rake the leaves in the garden alone in 24 minutes. His younger brother would take 30 minutes. How long would they dig a garden if Karel digs alone for 6 minutes and his brother comes to his aid? - The manufacturer
The manufacturer found that 3% of the plates produced had a malfunction. Of the complaint, 75% are first and 25% second. What is the probability of producing first and second-class plates? - Academy 23151
There are 180 pupils in the first year of the academy. Seven girls for every five boys, so there are how many girls in the year? - Probability
How probable is a randomly selected three-digit number divisible by five or seven? - The coal
The coal stock would be enough to heat a larger room for 12 weeks and a smaller one for 18 weeks. It was heated for four weeks in both rooms, then only in the smaller one. Thus, the coal stock was enough for how long? - The right triangle
The right triangle ABC has a leg a = 36 cm and an area S = 540 cm². Calculate the length of the leg b and the median t2 to side b. - Concentric circles and chord
In a circle with a diameter d = 10 cm, a chord with a length of 6 cm is constructed. What radius has the concentric circle while touching this chord? - The hollow cylinder
The hollow cylinder has a height of 70 cm, an outer diameter of 180 cm, and an inner diameter of 120 cm. What is the body's surface, including the area inside the cavity? - Cllub flag
The children had the club flag sewn on. The red color covered 2/20 of the flag's total area, the blue area a fifth, and the yellow 19% of the entire area. What percent is the green area occupied? - The four
The four pirates divided 65 coins into each other. They were sorted by age, the youngest receiving the least number of coins, each half more than the previous one. How many coins did the oldest pirate receive? - In a
In a triangle, the aspect ratio a: c is 3:2, and a: b is 5:4. The perimeter of the triangle is 74cm. Calculate the lengths of the individual sides. - Five letters
How many ways can five letters be arranged? - Digging
The first worker would dig a trench in 6 hours. For the second, the same work would take 4 hours. How long did it take for the trench to be dug if they worked together? - Closed circuit
There is a voltage source with U1 = 12 V in a closed circuit and with internal resistance, R1 = 0.2 Ω. The external resistance is R2 = 19.8 Ω. Find the electric current and terminal voltage. - Temperature 22861
The small bulb's socket has a reading of 6.3V/0.3A, which applies to its filament when the bulb is on. Determine the electrical resistance of the fiber under the given condition (the temperature of the fiber corresponds to about 2800°C) - Two-day trip Katy got a pocket trip for a two-day trip. She spent 3/5 on the first day and half the rest on the second. She brought home € 8. How many euros did Katy receive as pocket money?
- Rectangles 22781
A bricklayer has 48 tiles. How many different rectangles will he assemble? - Job applicants
Job applicants: three-fourths of applicants had experience in a position. The number that did not have prior experience was 36. How many people applied for the job? - Flakes
A circle was inscribed in the square. We draw a semicircle above each side of the square as above the diameter. This resulted in four chips. Which is bigger: the area of the middle square or the area of the four chips? - Remained 22741
There were apples on the table. Aleš took a quarter of apples, Bara a third of what remained. Cyril took half of the rest. Emil took the other four apples. How many apples were on the table in total?
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