Maths practice for 14 year olds - page 64 of 369

Number of problems found: 7376

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.
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.
Roland
Roland repairs and sells broken furniture. He pays $300 for a gaming chair and sells it for $408. What is his percent markup?
In the desert
A man wondering in the desert walks 5.7 miles in the direction S 26° W. He then turns 90° and walks 9 miles in the direction N 49° W. At that time, how far is he from his starting point, and what is his bearing from his starting point?
Inflated
By the time a man decided to buy a house, the cost had inflated by around 8% to £182,000. What was the approximate price before inflation?
Tristan
Tristan normally wrestles at 80 pounds. He wants to add enough weight to move into the 84-pound division. What percent of his current body weight must he add?

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