Math practice for 13 year olds - page 290 of 424
Number of problems found: 8465
- Last storm - tree
Mr. Radomír had a misfortune during the last storm; a tree fell on his roof in the shape of a regular four-sided pyramid and destroyed it all. The roof has a base edge length of 8m and a side edge length of 15m. How many m² of roofing will he have to buy? - Resistors 5915
If the current flowing through the first resistor is 200 mA and the second is 0.4 A, what will be the ratio of the first and second resistors connected in parallel? - Electric 5914
A current of 2 A at a voltage of 400 V passes through the electric motor. The electric motor is switched on for 0.5 h. What is the power input of the electric motor? - Bulb
A 60 W bulb consumes 0.12 kWh of electricity. How long did she stand light without a break? - The appliance
The appliance has a power input of 2.3 kW. It is connected to the mains voltage of 230 V. What is the current flowing through the appliance? - Water tank
A 288 hectoliter of water was poured into the tank with dimensions of 12 m and, 6 m bottom, and 2 m depth. What part of the volume of the tank water is occupied? Calculate the surface of the tank wetted with water. - Tourist 5910
The tourist went on a hike of 8 hours at a speed of 5 km/h. At 9:30, a cyclist set off behind him at a speed of 30 km/h. When will they meet? - Eva and
Eva and Jana have a total of 560 CZK. Eva has a third more than Jana. How much CZK does each have? - Turners
Two turners perform joint work in 3 hours. The first-turner would perform the job himself in 7 hours. How long would the same job last for a second-turner if he worked alone? - Cinema tickets
Cinema sold 180 tickets this Thursday, which is 20%. Monday 14%, Tuesday 6%, Wednesday 9%, Friday 24%, Saturday 12%, and Sunday 15%. How many tickets were sold per week? - Increased 5906
The number z increased by 20, which is 40% larger than the number z. Determine the number z. - Students 5905
There were 21 pupils in the class, and the teacher gave the mark one to 3 pupils, mark two to 5 pupils, mark three to 8 pupils, mark four to 4 pupils, and five to 1 pupils. How many percent of students received a grade better than three? - Rectangle area
The length of a rectangle is x units, and the width is y. Dimensions are increased by 10% and 15%, respectively. What is the ratio of the areas of the old and new rectangle? - Mixture 2
How many liters of water must be added to 7 liters of a 20% solution to obtain a 10% solution? - Equation 5900 Adam, Cyril, and Boris have a total of 102 CZK. How many crowns does Adam have, how many Boris and how many Cyril, if all three have the same when: a) Adam gives three crowns to Cyril b) Boris will give half of his money to Cyril c) Adam will give a third
- The train
The train passed the observer in the 20s and passed through a 1500m tunnel in 2 minutes. Calculate the speed (km/h) and train length. - The coil
How many ropes (a diameter of 8 mm) fit on the coil (threads are wrapped close together)? The coil has the following dimensions: The inner diameter is 400mm. The outside diameter is 800mm. The length of the coil is 470mm. - Cylindrical 5890
A cylindrical mug is packed in a 1-liter cube paper box. The mug is in close contact with all the walls of the cube. What volume is my mug? - The parallelogram
The circumference of the parallelogram is 79.5 m, and its shorter side is half the longer side. What is the length of which side of the parallelogram? - Advantage 5885
Boris and Braňo were on vacation by the sea with their parents. The stay cost the whole family 2170 euros. The trip price for a child was 115 euros lower than an adult's. Both boys took advantage of this discount this year. What was the price of the tour
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