Math practice for 13 year olds - page 348 of 413
Number of problems found: 8260
- Assistant
The Assistant rewrote 15% of the entire manuscript in 12 hours. How many hours must he still write to rewrite the rest of the manuscript? - Unknown number
Find an unknown number whose 1/5 is 40 greater than one-tenth of that number. - Disinfecting solution
How much distilled water is necessary to pour into 500 ml of 33% hydrogen peroxide to obtain a 3% disinfecting solution? - Saving
Paul saves 155Kč in 46 2 Kc and 5Kc coins. How much saved 2Kc and 5Kc coins? - 6 regular polygon
A regular six-sided polygon has a side 5 cm long. Calculate its area. Compare how many more cm² (square centimeters) has a circle inscribed the 6-gon. - Four classses
Students of all 7, 8, and 9 classes in one school may take up 4, 5, 6, and 7 abreast, and nobody will be left. If there are always four classes in each grade, what is the average number of pupils in one class? - Profitability
The purchase price of goods is 13000, and the sales price is 20000. What is the profitability as a percentage? - Complete construction
Construct triangle ABC if hypotenuse c = 7 cm and angle ABC = 30 degrees. / Use Thales' theorem - circle /. Measure and write down the length of the legs. - Circle r,D
Calculate the diameter and radius of the circle if it has a length 26.59 cm. - Robots Z7
In the school for robots, one class is attended by twenty Robert robots, numbered Robert 1 to Robert 20. There is currently a tense atmosphere in the class, only some robots are talking to each other. Robots with an odd number do not talk with robots with - Reducing number
Reducing the unknown number by 28.5%, we get the number 243.1. Find the unknown number. - Equation solving
Solve the equation: 3x-2 (x-1) = 1.5x + 0.5 (4-2x) - Tributaries
The first tributary fills the pool with water in 15 hours. The second tributary fills the pool in 10 hours. For how many hours is the pool filled with both tributaries? - Tonic
One package tonic consumes Mom for 12 weeks and the daughter for 14 weeks. They use the same cream together for four weeks and then only their daughter. How many weeks endured tonic to daughter then? - Bob and Bobek
Bobek runs from the hat at an average speed of 12 km/h at 10:20. At what time must Bob run out at a speed of 18 km/h to catch him 9 kilometers from the hat? - Dwarfs
Four dwarfs prepared firewood for Snow White and could finish in 580 minutes. After an hour and a half, they recruited friends and finished the work in 280 minutes. How many dwarfs did they recruit? - Arc-sector
arc length = 17 cm area of sector = 55 cm² arc angle = ? the radius of the sector = ? - Substitute a number
I think the number is when you substitute it in the expression (x-2). (2x - 1), you get zero. What number can it be? - Pedestrian and the cyclist
Pedestrians and cyclists went against each from the two cities that are distant 40 km. The pedestrian started 30 minutes before the cyclist and walked at an average speed of 5 km/h. What speed went the cyclist when met after 120 minutes from the start of - Beer permille
In the 5 kg of the blood of an adult human after three 10° beers consumed in a short time is 6.6 g of alcohol. How much is it per mille?
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