Math practice for 13 year olds - page 330 of 428
Number of problems found: 8549
- Car catching up
In the direction of Hradec Králové, a car left Prague at 8 hours at a 50 km/h speed. At 8 hours and 30 minutes, another car followed him at an average 70 km/h speed. How long will it take to catch up with the first car? - Block height
The block with a rectangular base measuring 18 cm and 11 cm has a surface of 1,556 cm square. Calculate the height of the block. - Block measurements
Calculate the solid diagonal of a block whose dimensions are: a = 3cm, b = 5, c = 7cm. Find its volume as well. - Percents of percentages
Calculate: (a) 5% of 25% of 85 b) 4% of 20% of 1500 c) 83% of 20% of 25 d) 0.3% of 70% of 90 - Number increase
Increase number 160 by: a) 25% b) 30% c) 150% - Square root sum
Determine the sum of the square roots of the number 25. - Average temperature
The following temperatures were measured every 6 hours from 6 to 24 hours: -2.2 C, 2.1 C, 5.4 C, 3.9 C, 0.7 C, -1.9 C, -3.8 C. Calculate the average temperature from 6 to 24 hours. - Area of a cube
Calculate the surface area of a cube if its volume is equal to 729 cubic meters. - Ball count
Roland has 490 balls. If he gave 145 bullets to Marek, he would still have 100 more bullets than Marek. How many balls did Marek have at the beginning? How many shots do they have together? - Dimensions of glass
An aquarium has 64 * 50 * 45 cm dimensions and is filled 5 cm below the upper edge. How many liters of water are in an aquarium? How many square meters of glass are needed to produce an aquarium? - Glass
How many glasses are needed to produce glass with a base of a regular 5-gon if one base triangle in the base is 4.2 square cm and the height is 10 cm? - Z9-I-4
Kate thought of a five-digit integer. She wrote the sum of this number and its half in the first line of the workbook. Write a total of this number and its fifth on the second line. She wrote a sum of this number and its one nines on the third row. Finall - Tunnels
Mice had built an underground house consisting of chambers and tunnels: • each tunnel leading from the chamber to the chamber (none is blind) • from each chamber lead just three tunnels into three distinct chambers, • from each chamber, mice can get to an - Unknown number
16% of the unknown number equals the square root of the number 25. Find this unknown number. - Square diagonal
Determine the diagonal of a square whose circumference is equal to 72 cm. - Average speed
What is the average speed you have to move around the world in 80 days? (Path along the equator, round to km/h). - Area and percents
Find what percentage is a smaller cube surface when the wall's surface area decreases by 25%. - Four-digit numbers
Create all four-digit numbers from digits 1,2,3,4,5, which can repeat. How many are there? - Cuboid enlargement
By how many percent increases the volume of the cuboid if every dimension increases by 30%? - Pet store
They sold fish from one aquarium from the breeding product (Zverimex). Ondrej wanted half of all the fish, but to avoid cutting any fish, he got half the fish more than he wanted. Matej wanted half of the remaining fish, but like Ondrej, he got half the f
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