Math practice for 13 year olds - page 316 of 413
Number of problems found: 8254
- Ravens
On two trees sits 17 ravens. If three ravens flew from the first to the second tree and five ravens took off from the second tree, then the first tree has two times more ravens than the second tree. How many ravens were originally on every tree? - Surface of wall
Find by what percentage the cube's surface will decrease if we reduce the surface of each of its walls by 12%. - Cube diagonals
Determine the wall and body diagonal of the cube, with the surface of one of its walls being 121 square centimeters. - Wheel diameter
What is the diameter of the wheel when it turns 455 times per 1 km? They rounded to the nearest cm. - Circle in rectangle
We cut the largest possible circle from a paper rectangle with 25 cm and 15 cm sides. How many % of the area of the rectangle is the area of the circle? - Vacuum efficiency
Determine the efficiency of a vacuum cleaner with a power input of 1.2 kW when the suction power is 360 W. - Efficiency
What is the power output of a kettle 2 kW with an efficiency of 90%? - Plane II
A plane flew 50 km on a bearing of 63°20' and then flew in the direction of 153°20' for 140 km. Find the distance between the starting point and the ending point. - Square root sum
Determine the sum of the square roots of the number 12. - Cylinder surface
Find the surface of the cylinder if its diameter is 12 centimeters and its height is 9 centimeters. - Percentage calculation
0.6 percent of n is 18. calculate n. - Triangle angles
Calculate the size of the interior angles of a triangle if the size of the second angle is 120 degrees less than twice the size of the first angle and the size of the third angle is equal to the difference between the sizes of the first and second angles. - Bar cuts
Peter cut the two bars into equal parts but made them as large as possible. One rod measured 42 cm, the other 63 cm. How many cuts did he have to make? - Field planting
The 102-hectare field is to be sown with flax and planted with potatoes. The area sown with flax should be three times smaller than the exchange planted with potatoes. Which acreage should be planted with flax, and which should be planted with potatoes? - Wall diagonal Calculate the length of the face diagonal of the cube, whose surface is 384 cm square.
- Dried apples
How many kilograms of fresh apples are needed for 120 kg of dried apples when we get 75 kg of dried apples from 0.4 tons of fresh apples? - Rational equation
x-2 / x-1 -2 = x + 1 / x-2 - Temporary sale off
With a temporary price reduction, the jacket's original fee of CZK 1,850 was reduced by 20%. Later, it was raised again by 20%. What was the jacket's final price? - Number probability
There are numbers from 1 to 20 in the hat. What is the probability that we will pull out from the hat: a / one-digit number b / prime number c / number greater than 11 d / a number divisible by six Thank you - Baking bread
When grinding 100 kg of grain, we obtain 75 kg of flour for food purposes, about 23 kg of bran, which has further use, and about 2 kg is waste. 4.5 kg of bread is baked from 4 kg of flour. a) Baker can bake how many kilograms of bread from 100 kg grain? b
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