Math practice for 13 year olds - page 407 of 419
Number of problems found: 8372
- Bath
There are 30 liters of hot water in the bath. Then we added 39 liters of cold water at a temperature of 19 °C and decreased the temperature of the water to 45 °C. What was the initial temperature of the hot water? - Solution
In 469 dl, the red solution is 84 dl in red color, and in 102 dl, the blue solution is 52 dl in blue color. How many dl of red and blue dl color solution must be mixed to get a mixture of 247 dl to contain 116 dl of color? - Warehouses
To four warehouses is going cement in 50 kg bags, from first one third to the second quarter of the total. The third store got two-thirds of the rest, and the last 120 tons came to fourth. How much cement is in all warehouses, and how much got everyone? - IS trapezoid
Calculate the length of diagonal u and height v of isosceles trapezoid ABCD, whose bases have lengths a = |AB| = 37 cm, c = |CD| = 29 cm and legs b = d = |BC| = |AD| = 28 cm. - Scrap
From 18 products are 5 scraps. What is the probability that the random pick of 2 products has no defective product? - Regular 5-gon
Calculate the area of the regular pentagon with side 16 cm. - Tape
Video is 199% more expensive than a tape recorder. How many percent is a tape recorder less expensive than a video? - Spherical cap
From the sphere with a radius of 26 was a truncated spherical cap. Its height is 2. What part of the volume is a spherical cap from the whole sphere? - Rectangular cuboid
The rectangular cuboid has a surface area 4131 cm², and its dimensions are in the ratio 2:4:5. Find the volume of this rectangular cuboid. - Troops
The route is long 175 km. On the first day, the first regiment went at an average speed of 14 km/h and back at 24 km/h. On the second day, the second regiment went on the same route at an average speed of 25 km/h there and back. Which regiment will take t - Pizza
A school survey found that 10 out of 15 students like pizza. If 5 students are chosen randomly, what is the probability that all 5 students like pizza? - 2x cone
Circular cone height 36 cm was cut plane parallel with the base. The volume of these two small cones is the same. Calculate the height of the smaller cone. - Pediatrician
Pediatrician, this month of 20 working days takes 4 days holidays. What is the probability that it will be at work on Monday? - Cone
The circular cone of height 14 cm and volume 4396 cm³ is at one-third of the height (measured from the bottom) cut by a plane parallel to the base. Calculate the radius and circumference of the circular cut. - Medians
Calculate the sides of a right triangle if the length of the medians to the legs are ta = 25 cm and tb=30 cm. - Rectangle
In rectangle ABCD with sides, |AB|=19, |AD|=19 is from point A guided perpendicular to the diagonal BD, which intersects at point P. Determine the ratio r = (|PB|)/(|DP|). - Rhombus
It is given a rhombus with a side length of a = 20 cm. Touchpoints of the inscribed circle divided its sides into sections a1 = 13 cm and a2 = 7 cm. Calculate the radius r of the circle and the length of the diagonals of the rhombus. - Freedom
In the city are 2/4 of women married for 4/6 men. What proportion of the townspeople is free (not married)? Express as a decimal number. - Cube in a sphere
The cube is inscribed in a sphere with a volume 8101 cm³. Determine the length of the edges of a cube. - Motion problem
From Martina to Levíc, go car at speed 89 km/h. From Levíc to Martina, go another car at speed 71 km/h. How many minutes before the meeting will be cars 29 km away?
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