Math practice for 13 year olds - page 85 of 428
Number of problems found: 8558
- Aquarium volume half
Pavel has a cube-shaped aquarium with a volume of 240 liters. Thomas has an aquarium whose all dimensions are half the dimensions of Paul's aquarium. What is the volume of Thomas's aquarium? - Bear weight percentage
The bear weighed 410 kg at the beginning of winter and lost 10 percent during hibernation. He gained 10 percent of his weight from spring to fall. Find out if the bear's weight was greater at the beginning of winter or autumn by what percentage. - Cooker efficiency testing
When testing the effectiveness of an electric cooker with data of 220 V, 1200 W, 1 kg of water at a temperature of 15 degrees Celsius was boiled for 8.5 minutes. Calculate the stove efficiency corresponding to these data - Percentage twelve sixty
Calculate what percentage is 12€ of 60€. - Current wire resistance
The current I = 4A branches into three wires with resistances R1 = 2Ώ, R2 = 5Ώ, R3 = 10Ώ. Calculate the total resistance of the connection and the voltage of the source. How big are the currents in each wire? - Current in the bulb
The bulb is rated 6 V, 0.2 A. Determine the current rating of the bulb. - Circuit breaker power
The electric circuit breaker automatically switches off the circuit of the 220 V electrical network at a current of 6 A. Determine the maximum power in the protected circuit. - Cooker heat generation An immersion cooker has a resistance of 30 ohms and is connected to a voltage of 120 V. How much heat is generated in 2 hours?
- Bulb consumption hours A current of 500 mA passed through the filament of a light bulb with a resistance of 400 ohms. What is the consumption of a light bulb in 5 hours?
- Cooker plate resistance The immersion cooker plate has data 220 V, 300 W. What is the resistance of the heating wire?
- Iron plate resistance The electric iron plate has written 220 V, 1200 W. What is the resistance of the heating wire?
- Triangle middle crossbar
Calculate the length of the middle crossbars in an isosceles triangle if the length of the arm is 52mm and the base height is 48mm - Worker hourly output
A worker makes 12 furs in 12 hours. One truck has 20 m³. The price for the application is 2.45 euros/m³. What will be the hourly output in euros? - Sweater quality percentage
Out of 400 sweaters, 5% are second quality, and the rest are first quality. How many sweaters are of first and second quality? - Train pursuit meeting
A train travels at a speed of 50 km/h from city A. In 15 minutes, a second train follows him at 20 m/s. We are sitting on the first train. When will the second train catch up with the first? - Farm animal legs
There are cows, ducks, and geese on the farm. They have a total of 126 legs. Ducks are 3 more than houses. And there are 20 cows. If we count all the animals, we have to divide them by the number three, and we should get a single-digit number. - Milk cream butter
On average, 100 liters of milk make 16 liters of cream, and 100 liters of cream make 20 liters of butter. How many liters of milk do we need for 100 liters of butter? - Strawberries - shop
Mom and grandma went shopping at the market. Mom bought 2 kg of strawberries and 3 liters of blueberries and paid 250 CZK. Grandma bought 1 kg more strawberries and 0.5 l fewer blueberries than mom and paid 45 CZK more than her. How much did 1 kg of straw - Grandparent age average
The average age of the grandfather, grandmother, and their five grandchildren is 26 years. The average age of the grandchildren themselves is 7 years. Grandma is a year younger than grandpa. How old is grandma? - Chord center distance
Calculate the distance of a chord 19 cm long from the center of a circle with a diameter of 28 cm.
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