Math practice for 13 year olds - page 377 of 422
Number of problems found: 8427
- Digits A, B, C
For the various digits A, B, and C is true: the square root of the BC is equal to the A, and the sum B+C is equal to A. Calculate A + 2B + 3C. (BC is a two-digit number, not a product). - Miraculous tree
The miraculous tree grows so fast that the first day increases its height by half the total height of the second day by the third, the third day by a quarter, etc. How many times will it increase its height after 6 days? - The rod
The rod is painted in four colors. 55% of the bar is painted blue or green, 0.2 of the rod, 1/8 is brown, and the remaining 45 cm is white. How long is the rod? - Water well
A drilled well has a depth of 20 meters and a radius of 0.1 meters. How many liters of water can fit into the well? - Polygon 42
Which polygon has 42 more diagonals than sides? - Concrete pipe
How much will it cost to cover a 6 m long concrete pipe with an outer radius of 1.5 m and an inner radius of 0.8 meters if one m² paint costs 24 €? - Circular lawn
Around a circular lawn area is a 2 m wide sidewalk. The outer edge of the sidewalk is a curb whose width is 2 m. The Curbstone and the inner side of the sidewalk together form concentric circles. Calculate the area of the circular lawn, and the result rou - Rhombus base
Calculate the volume and surface area of prisms whose base is a rhombus with diagonals u1 = 17 cm and u2 = 14 cm. The prism height is twice the base edge length. - Tray
If the water level in the tray shaped as a cuboid is 420 liters and the bottom dimensions are 120 cm and 70 cm, what height reaches the water level? - For thinkings
The glass cube dives into the aquarium, which has a length of 25 cm, a width of 20 cm, and a height of 30 cm. Aquarium water rises by 2 cm. a) What is the volume of a cube? b) How many centimeters measure its edge? - Two cars
From A town started two cars to town B. The first begins at 7:00 at an average speed of 60 km per hour. The second car starts at 10:00 at an average speed of 100 km per hour. The first car will not stay in B, and on the way back, meet the second car halfw - Hollow sphere
The hollow steel sphere floats on the water, plunged into half its volume. Determine the outer radius of the sphere and wall thickness if you know that the weight of the sphere is 0.5 kg and the density of steel is 7850 kg/m³ - Aircrafts
The bomber started at 9:00 from the airport and flew at an average speed of 1850 km/h toward Airfield B, a distance of 3500 km. After evaluating the danger from the airport, B started at 9:45 B towards A fighter at an average speed of 2300 km/h. At what t - Volume from surface area
What is the volume of the cube whose surface area is 96 cm²? - Inscribed triangle
A circle is an inscribed triangle, and its vertices divide the circle into three arcs. The length of the arcs is in the ratio 2:3:7. Find the interior angles of a triangle. - Interest p.a.
Calculate the value of the interest in the period of 1 year from the deposit 62000 CZK at 8 percent interest rate after deducting 15 percent tax. - Warehouse cars
From the warehouse, a truck started at a speed of 40km/h. After 1 hour 30 mins started from the same place in the same direction a car at 70 km/h. For how long and at what distance from the warehouse overtake a truck? - Circle inscribed
Calculate the perimeter and area of a circle inscribed in a triangle measuring 3, 4, and 5 cm. - Gloves
I have a box with two hundred pieces of gloves in total, split into ten parcels of twenty pieces, and I sell three parcels. What percent of the total amount I sold? - 3 years
The company has increased the number of employees. In year 1994 compared to 1993 19% more, in 1995 14% more against the previous year, in year 1996 20% more compared to 1995. How much percent increase in the number of employees in 3 years?
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