Math practice for 13 year olds - page 312 of 428
Number of problems found: 8548
- Hostel rooms
There are 32 rooms in the hostel. Some have double beds, others have four beds and the rest have 7 beds. There are a total of 139 beds in the hostel. How many are there if a two-digit number gives the numbers of individual species? - Coin count
Eva had seven coins. Crowns, two-crowns, and five-crowns. At least two of each. How many did she have if she could buy three packs of gum for six crowns? - Weight puzzle
A + B weighs 75 kg, B + C weighs 83 kg, C + D weighs 92 kg. How much does A + D weigh? - Disc
The circumference of the disk is 78.5 cm. What is the circumference of the circular arc of 32° on the disc? - Triangle similarity
Find out if the triangles ABC and A'B'C' are similar, determine the similarity coefficient and write the similarity: a = 40 mm, b = 48 mm, c = 32 mm a´ = 60 mm, b´ = 50 mm, c´ = 40 mm - Sides of the triangle
The sides of the triangle ABC have a length of 4 cm, 5 cm, and 7 cm. Construct triangle A'B'C', similar to triangle ABC, which has a circumference of 12 cm. - Map scale
On a 1:1000 scale map is a rectangular land of 4.2 cm and 5.8 cm. What is the area of this land in square meters? - Map scales
Two places have a distance of 4 cm on a map with a scale of 1:75 000. What is their distance on a 1:50,000 scale map? - Bun distribution
The two Honzos had buns. The first 6, the second 4. They split with their grandmother so that they all had the same amount. Grandma gave them 5 apples. The first wanted 3, the second wanted 2. The second wanted, on the contrary, Grandma recommended dividi - Segment length
Calculate the length of the line segment AB, given A [8; -6] and B [4; 2] - Chronicle cipher
From the beginning of the year, students in 4th grade wrote a chronicle. She had everything they had together, and they cared a lot about her. But one day, the chronicle was lost. Five students were left to search for everything on Monday after the class. - Socks
One pair of socks is worth CZK 27. A set of three pairs of these socks is sold with a 10% discount. How much will we pay for two offered sets of socks? - Storm
So far, a storm has traveled 35 miles in 1/2 hour in a direction straight to the observer. If it is 5:00 PM, and the storm is 105 miles away from you, at what time will it reach you? Explain how you solved the problem. - Tunnel travel time
How long will a 1 km long tunnel take to travel at a speed of 100 km per hour? - Runners lapping
Two runners run on a 3200m oval track, one running at 12 km/h and the other at 8 km/h. How long does it take for the first runner to finish the second one? - Pond sluice
The first sluice empties a complete pond in 45 days. If 2/3 of the pond is drained in 15 days, a second sluice is still needed for ten days. How many days would it empty itself through just the second sluice? - Salt
Seawater containing 5% salt. How many kilograms of fresh water is necessary to pour into 40 kg of seawater so that the salinity falls to 2%? - Trapezoid
How long are the trapezoid bases with an area of 24 cm² and a height of 3 cm? One base is three times longer than the shorter. - Megapascals
What is the area of cross-section of the piston if the force of 300 kN produces a pressure of 5 MPa? - Rope
How many meters of rope 10 mm thick will fit on the bobbin diameter of 200 mm and a length of 350 mm (the central mandrel has a diameter of 50 mm)?
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