Themes, topics - practice for 13 year olds - page 3 of 82
Number of problems found: 1640
- Transformer 3
A 200/115 V transformer has an LV (Low voltage) side resistance of 0.06 Ohm. What is the resistance referred to HV side (high voltage)? - Ronaldo
Ronaldo drove 75 3/5 km in 4 1/2 hours. What was the average speed? - The distance 3
The distance covered by car in 1 hour is 38 1/2 km. Find the distance it will cover in a) 3 1/2 hours, b) 5 hours. - The temperature 38
The temperature has been dropping 2 degrees every hour, and the temperature at 10:00 AM was -15 degrees Fahrenheit. At what time was the temperature 0 degrees Fahrenheit?
- Iron ball 2
What is the mass of the iron ball with a diameter of 1,0 dm? The density of iron is 7870 kg/m³. . - Granddaughters 83342
Granddaughter Mia helped the old for 3 days, Ema for 2 days, and Zoja for 4 days. If the grandmother wants to reward her granddaughters fairly according to how long they have been helping her, in what proportion should she divide the chocolate among her g - Doubravka 83293
Evelyn plows the garden in four hours, while her friend Doubravka can do it in three hours. Evelína started work at 1 p.m., and an hour later, Doubravka joined her so they could go swimming together. Calculate the time the girls can go to the swimming poo - Another 83290
Petra pushed a chair from one room to another with a force of 60N. She did 300 J of work. How far did Petra push the chair? - Together 83245
Jarka and Jana decided to decorate their common room. If Jarka painted it alone, it would take her 4 hours, and Jane 3 hours. How long would they paint the room if they painted together?
- Dimensions 83226
Calculate the weight of an iron bar 1.2 m long, whose cross-section is a trapezoid with dimensions a=10 cm c=8 cm and the distance between the bases v=6 cm. As we know, 1 cubic meter of iron weighs 7800 kg. - Actually 83215
The square-shaped plot actually covers an area of 81 ares. Maybe draw it in the village plan on a scale of 1:200. What will be the length of the side on the plan? - Liters 83211
We have 160 L of water at 67°C; how many liters of cold water at 18°C are needed to cool it to 39°C? - Families 83209
Coal for 15 families lasts 60 days. How many days will the coal last for 20 families? - Weighing 83201
Bronze is an alloy of copper and tin in a ratio of 1:4. How much copper does a bronze piece of jewelry weighing 25 g contain?
- Construct 83195
Two line segments of different lengths are given. Construct a circle k so that both line segments are its chords. - Seamstresses 83192
Three sewers sew 7 skirts in 15 hours. How many skirts can 2 seamstresses make in 50 hours? - Braking 83146
A car of mass m=1t moves at a speed v0=54 km/h. What braking force must be exerted to bring the car to a stop in 10 seconds, and how far will the car travel in this time? - Bobsleigh 83132
Behind the pond, the cat Mikeš skis and bobsleds a 300-meter-long slope that a careful bobsleigh can go down in a minute. If Mike is down 20 seconds earlier, how many km/h is He going down the hill faster than Bobes? - Distilled 83093
The 50% salt solution must be diluted with distilled water to make 20 liters of 35% solution. How many liters of original solution and how many liters of water do we need?
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