Math practice for 13 year olds - page 434 of 436
Number of problems found: 8719
- Two doctors
Doctor A makes the correct diagnosis with a probability of 89% and Doctor B with a probability of 75%. Calculate the probability of a correct diagnosis if both doctors examine the patient independently. - Present
A gift box has the shape of a cuboid with dimensions 8 × 8 × 3 cm. Miloslav wants to wrap it using square sheets of paper with sides of 18 cm. How much paper is left over? - Monkey
The monkey fell into 20 meters deep well. Every day it climbs 3 meters, at night it drops back by 2 m. On what day it gets out from the well? - Mine
The wheel in a mine hoist has a diameter of 4 m. How many metres does the elevator cabin travel if the wheel rotates 89 times in the same direction? - Clocks
How far does the tip of a clock's minute hand travel in 340 minutes if the minute hand is 23 cm long? How far does the tip of the hour hand travel in the same time? - Cone in cylinder
The cylinder is an inscribed cone. Find the ratio of the volume of the cone and cylinder. Please write the ratio as a decimal number and as a percentage. - Cone in cube
The cube is an inscribed cone. Determine the ratio of the volume of the cone and cube. Please write the ratio as a decimal number and as a percentage. - Kites
Boys fly kites on cables 68 metres long. What is the altitude of a kite if the cable makes an angle of 72° with the horizontal? - Ladislav in Amsterdam
Larry was sent to a conference in Amsterdam as a reward. The conference fee was €1702. Calculate how many books Larry could buy at prices of 30 and 28 euros each, given that he does not want to fill his entire home library and may buy only 59 books in tot - Chess
How many ways can you select 4 fields on a classic chessboard with 64 fields so that fields don't have the same color? - Maximum area of rhombus
At what interior angles does a rhombus have the maximum area? - Lunch for free
Meal vouchers are a tax-free employee benefit widely used in Slovakia. The company issuing meal vouchers charges a 4.3% fee on their total value. Calculate how much an employee effectively receives if they get 201 meal vouchers worth 3.2 € each per year. - Number ratio
Calculate two positive numbers. Its ratio is 6:18, and difference was 372. - Road
Between cities A and B there is a route 9 km long with an average gradient of 9‰ klesanie. Calculate the height difference between cities A and B. - Farmer
A farmer cultivates 244 ha of arable land, which represents the part of his land that is not meadows and pastures. The remaining 12% consists of meadows and pastures. How much land does the farmer own in total? - Angles in triangle
In a triangle, the ratio of angles β to γ is 6:8. Angle α is 40° greater than β. What are the sizes of the angles of the triangle? - Jewel
A rhombus-shaped jewel has an area of 23 mm² and a side length of 5.9 mm. Calculate the size of the acute angle of the rhombus. - Rhombus HP
Calculate the area of a rhombus with height 48 cm and perimeter 64 cm. - Drunk man
The drunk man has 2.6‰ of alcohol in his blood. How many grams of alcohol has in his blood if he has 5 kg of blood? - Cube wall
The surface of the first cube wall is 64 m². The second cube area is 40% of the surface of the first cube. Find the length of the edge of the second cube (x).
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