Math practice for 13 year olds - page 61 of 421
Number of problems found: 8410
- Calculate 82808
Calculate the radius of an iron ball with a density of 7.8g/cm³ and a mass of 7kg. - Cashier 82807
To pay out the amount of CZK 570, the cashier used 15 coins: a few fifty crowns and a few twenty crowns. How did she pay the amount? - Open simultaneously
An empty tank is filled with inflow in 30 minutes. A full tank is emptied in 75 minutes with an open drain. How long does it take for an empty tank to fill up if both the inlet and outlet are open simultaneously? - Elevation angle
An airliner currently flying over a location 2,400 m away from the observer's location is seen at an elevation angle of 26° 20'. At what height does the plane fly? - Workers 82802
Five workers do a job in 20 hours. How long will it take two workers to do the same job? - Accumulator 82755
The battery capacity is 50 Ah. With a current of 5A, we charge the accumulator to 100% capacity in 10 hours. To what percentage of capacity can we charge the accumulator with a current of 2A in 15 hours? - Justify
50 bottles of red wine are purchased for a company party. In the first store, a bottle of wine costs €6.90. Here they have a promotion that when you buy 4 bottles, the fifth one is free. In the second store, the same bottle of wine costs €8.50. However, t - Overtake 82752
I am passing a tractor whose speed is 20 km/h. The length of the tractor with the siding is 10 m. My speed is 50 km/h. How long will I overtake the tractor? - Intervention 82748 The missile flies towards the plane at a 2000 km/h speed. The speed of the plane is 1000 km/h. The intervention is after 1.5 minutes. How far apart were the rocket and the aircraft in the beginning?
- Quadrilateral pyramid
Construct a 3D model of a quadrilateral pyramid with a rectangle base and sides of isosceles triangles, with a volume of 80 cubic cm. I need to know the sides and the height. - Children's 82745
The children's car has wheels with a radius of 15 cm, and its speed is 36 km/h. How many times does the toy car wheel turn in a minute at this speed? - Branches 82741
The meadow has massive trees, a lake, and tall grass. A seventh of the birds sit in nests in trees. A third swim in the lake and a quarter of the birds sit in nests in the tall grass. Twenty-three birds are sitting on tree branches. How many birds are the - Containers 82736
Two filling machines fill 250 containers in 2 hours. How many containers will 4 machines fill in 3 hours? - Kilometers 82735
Fifteen kilometers in front of us, a car travels at a speed of 70 km/h. We drive at an average speed of 100 km/h. How many minutes will it take us to catch up with the car? - Boiler room
If only the first boiler is running, the coal supply is enough for 8 days. If only the second boiler is running, the coal supply is enough for 12 days. If only the third boiler is in operation, the coal supply will last for 6 days. How many days in total - Refrigerator - discount
The refrigerator was first discounted by 20% and then increased in price by 5%. Now the Zmrzlin family bought it for 420 euros. How much was the refrigerator before the discount? - Individual
To prepare 14 kg of cheese with 45% dry matter, 3 types of cheese mixtures were mixed. The first was 5 kg, the second was 3 kg and had 14% more dry matter (14 percentage points more) than the first. The third mixture, which had 2 times as much dry matter - Occupied 82715
Fifty pupils were in the camp; they lived in double and triple rooms. They occupied 20 rooms, many of which were two- and three-story. Please proceed. - Resistance 82714
A load of 23.5 ohm is connected to an ideal voltage source of 30V, and a current of 1.2A passes through the circuit. Determine the magnitude of the source's internal resistance and the short-circuit current. - Consecutive 82712
The sum of five consecutive even numbers is -10. What are the numbers?
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