Math practice for 13 year olds - page 237 of 428
Number of problems found: 8556
- Age question
Jano is three times older than Zdeno. Zdeno is 12 years younger than Janko. How old is Jano, and how old is Zdeno? - RPM
An electric motor makes 3,000 revolutions per minute. How many degrees does it rotate in one second? - Chessboard piece placement
Determine how many ways we can place 5 different pieces on an 8x8 chessboard so that two are on black squares and three are on white squares. - Balls
From the bag with numbered balls (numbers 1,2,3,. ..20), we pick one ball. What is the probability of choosing a number containing 1? - Athletic club
All athletic club boys lined up by size. In front of Peter was one-eighth of the total. Right behind Peter stood his brother Radek and behind Radek, another five-sixths of the total number of boys. Mark the unknown total number of athletic club boys x. 1, - Time passing
Six years ago, Marcela's mother was two times older than her and two times younger than her father. When Marcela is 36, she will be twice as young as her father. How old are Marcela, her father, and her mother now? - Average speed
The truck drove 1/2 of the way on the highway at 80 km/h. The other half of the way, 20 km/h. Calculate the average speed. - Illness absence percentage
The clerk will work 178 hours a month. She missed 54 hours due to illness. What percentage is it? - Three pumps together
One pump fills the tank in 1.5 hours, the second in 2 hours, and the third in 3 hours 20 minutes. How many minutes will the tank fill with three pumps if they work simultaneously? - Pebble
The aquarium is filled with two-thirds water with internal dimensions of the bottom 40 cm × 35 cm and a height of 30 cm. Calculate how many millimeters the water level in the aquarium rises by dipping a pebble-shaped sphere with a diameter of 18 cm. - Wooden ball diameter A solid wooden ball made of beech wood weighs 800 g. Calculate its diameter if the wood density is pi = 750 kg/m3
- Steel tube
The steel tube has an inner diameter of 4 cm and an outer diameter of 4.8 cm. The density of the steel is 7800 kg/m³. Calculate its length if it weighs 15 kg. - Bicycle pursuit calculation
The first patrol of the pupils' orientation run started at 8 a.m. at an average speed of 5 km/h. At 8:36 AM, the leader of the orienteering race followed them on a bicycle at a speed of 20 km/h. When and how far from the start will he catch up with them? - Copper sulphate
How much g of water do we have to add to 240 g of an 84% CuSO4 solution to produce a 60% solution? (Express the mass of crystalline CuSO4 in the original solution and the resulting solution and compare them. ) - Sales off
After discounting 40%, the goods cost 15 €. How much did the cost of the goods cost before the discount? - Dice even probability
We roll two different dice. What is the probability that a pair of even numbers will fall? - Garden scale area
The garden has an area of 5000 m². What is its image area on a 1:1000 scale on the plan? - The second
The second angle of a triangle is the same size as the first angle. The third angle is 12 degrees larger than the first angle. How large are the angles? - Drilling machine
A manufacturing firm purchased a heavy-duty drilling machine. They were given two payment options: Option 1: Make a payment of $46,000 immediately to settle the invoice for the machine. Option 2: Pay $21,500 immediately and the balance of $23,550 in 3 mon - Motorcyclist average speed
The motorcyclist was riding: a) the first half of the driving time at a speed of 30 km/h, the second half of the time at a speed of 60 km/h, b) the track's first half at a speed of 30 km/h and the second half at a speed of 60 km/h. Determine its average s
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