Maths practice for 14 year olds - page 65 of 369
Number of problems found: 7373
- Hibernation 80718
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. - Average of average
Three different numbers are given. The average of the average of two smaller numbers and the average of the two larger numbers is equal to the average of all three numbers. The average of the smallest and largest number is 2022. Determine the sum of the t - Effectiveness 80711
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 80710
Calculate what percentage is 12€ of 60€. - Resistances 80706
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? - Automatically 80704
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. - Resistance 80703 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?
- Consumption 80702
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? - Resistance 80699 The immersion cooker plate has data 220 V, 300 W. What is the resistance of the heating wire?
- Resistance 80698 The electric iron plate has written 220 V, 1200 W. What is the resistance of the heating wire?
- Crossbars 80697
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 - Sweaters 80695
Out of 400 sweaters, 5% are second quality, and the rest are first quality. How many sweaters are of first and second quality? - Single-digit 80674
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. - 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 - Grandchildren 80639
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? - Calculate 80636
Calculate the distance of a chord 19 cm long from the center of a circle with a diameter of 28 cm. - Two-thirds 80635
The car traveled the first third of the track with a constant speed of v1, the next two-thirds of the way at a constant speed of v2=72km/h, and the average speed of v=36km/h. Find v1. - Acceleration 80626 The car stopped at an initial speed of 90 km/h on a track of 62.5 m. What was its acceleration, and how long did it take to brake the car?
- Participated 80621
Three 9th-grade classes participated in the paper collection competition. The company bought 1 kilogram of paper for €0.12, and the school received €174 thanks to their hard work. Calculate how many kg of paper 9A collected if you know that she collected - Difference 80618
A regular hexagon is described and inscribed in a circle. The difference between its areas is 8√3. Find the circle's radius.
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