Math practice for 13 year olds - page 64 of 414
Number of problems found: 8262
- Cashier coin payment
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? - Worker job hours
Five workers do a job in 20 hours. How long will it take two workers to do the same job? - Battery charging capacity
The battery capacity is 50 Ah. With a current of 5 A, we charge the accumulator to 100% capacity in 10 hours. To what percentage of capacity can we charge the accumulator with a current of 2 A in 15 hours? - Justify
50 bottles of red wine are to be purchased for a company party. In the first store, a bottle of wine costs €6.90, and they have a promotion where every fifth bottle is free when you buy four. In the second store, the same bottle costs €8.50, but there is - Tractor overtaking time
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? - Missile plane distance 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. - Car wheel rotation
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? - Meadow bird distribution
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 - Machine container filling
Two filling machines fill 250 containers in 2 hours. How many containers will 4 machines fill in 3 hours? - Car pursuit minutes
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 lasts 8 days. If only the second boiler is running, the supply lasts 12 days. If only the third boiler is running, the supply lasts 6 days. How many days in total will the coal supply last if only the f - 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, three types of cheese mixtures were blended. The first mixture weighed 5 kg; the second weighed 3 kg and contained 14 percentage points more dry matter than the first. The third mixture, which had twice the - Camp room distribution
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. - Source internal resistance
A load of 23.5 ohm is connected to an ideal voltage source of 30 V, and a current of 1.2 A passes through the circuit. Determine the magnitude of the source's internal resistance and the short-circuit current. - Consecutive even sum
The sum of five consecutive even numbers is -10. What are the numbers? - Part-timer
Seven part-timers paint 280 m of railings in 5 hours. How many meters of railing will nine part-timers paint in 4 hours?
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