Math practice for 13 year olds - page 237 of 425
Number of problems found: 8485
- 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. - Calculate 8881 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. - Orienteering 8851
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? - Probability 8801
We roll two different dice. What is the probability that a pair of even numbers will fall? - 5000 8761
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 8671
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 - Complied 8661
Police found that the car had traveled 300m in 20 seconds. He complied with the driver's maximum allowed speed of 50 km/h - Proportion 3
For every eight mango trees in the orchard, there are 4-star apple trees. If there are 1320 trees, how many trees of each kind are there? - Discount 8631
The dress cost a thirty percent discount of CZK 1,680. How many crowns did they cost before the discount? - Determine 8611
Determine all natural numbers A and B pairs for which the sum of twice the least common multiple and three times the greatest common divisor of natural numbers A and B is equal to their product. - Excavation 8581
When building a new road, excavating a 280m long road in the ground was necessary. The bottom width, where the road runs, was 20m wide. At the top, the entire excavation was 30m wide. The depth of the excavation is 6 m. How much m³ of soil had to be remov - Drive to NJ
Ed drove to New Jersey at 30mph. He drove back home in 3 hours at 50 mph. How many hours did it take Ed to drive to New Jersey? - Concrete curb
The concrete curb has a width of 20 cm at the bottom and 15 cm at the top. It is 20cm tall. Its length is 80 cm. The density of concrete is p=2100kg/m³. How many can Mr. Havlík load on a trailer for a car if the trailer has a load capacity of 400 kg? - Dice and coin
A number cube is rolled, and a coin is tossed. The number cube and the coin are fair. What is the probability that the number rolled is greater than two and the coin toss is head?
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