# Themes, topics - practice problems

#### Number of problems found: 1221

- Voltmeter range

We have a voltmeter which in the original set measures voltage to 10V. Calculate the size of the ballast resistor for this voltmeter, if we want to measure the voltage up to 50V. Voltmeter's internal resistance is 2 kiloohm/Volt. - Coils of transformer

The primary coil of the transformer has 1100 turns and is connected to a voltage of 220V. How many turns does the secondary coil have when the voltage on it is 55 V? Find the transformation ratio and decide what kind of transformation. - Cyclo trip

Eighth-graders took a full-day trip on a cycling course. They took 1/7 of the route to the first break and added another 3/7 of the route to lunch. They had 18 km left to the finish. How many kilometers did the trip route measure? - Three resistors

You have to connect three identical resistors with 12 Ohm resistances so that you gradually get the resulting resistance a) 36 Ohm, b) 4 Ohm, 18 Ohm. Draw a diagram of each circuit. - Bonbons 2

Kilo sweets will cost 260 CZK. The first type has a price per 320 kg, the second type 240 CZK per kg. How many kilos of both kinds of sweets need to prepare a 35 kg mixture ? - Orlík hydroelectric plant

The Orlík hydroelectric power plant, built in 1954-1961, consists of four Kaplan turbines. For each of them, the water with a flow rate of Q = 150 m^{3}/s is supplied with a flow rate of h = 70.5 m at full power. a) What is the total installed pow - 24carat gold

The goldsmith cast 22 carat gold and 14 carat gold and earned 20 dkg of 18 carat gold. How much gold did he use? - Together

Grandfather, father, and son are carpenters. They decided to make a wardrobe. Father produces it for 12 hours, his son for 15 hours, and grandfather for 10 hours. How long will they make it together? - King's birthday

To celebrate the king's birthday workers fire 1/5 all purchased rockets. To celebrate the Queen's birthday fire 1/6 of the remaining rockets and to celebrate the birthday of king's son remaining 15,000 rockets. How many rockets they purchased? - Tulips and daffodils

Two hundred twenty tulips and daffodils are planted in the flowerbed. One-third of all tulips and one-sixth of all daffodils equals the number of all tulips. How many tulips and how many daffodils? - Cottages

The summer camp is 41 cottages. Rooms are for three and four in them. How many of the 140 campers lives of three? - Two resistors

Two resistors when they give 25 ohms in series and 4 ohms in parallel what the values of - Crown

Siblings collect a 2-crowns and 5-crowns. Together have 80 coins with a total of value 310 crowns. How many saved two-crowns and how many five-crowns? - Resistors

Two resistors connected in series give the resulting resistance 240Ω and 57.6Ω in parallel. Determine the resistance of these resistors. - Open intervals

Open intervals A = (x-2; 2x-1) and B = (3x-4; 4) are given. Find the largest real number for which A ⊂ B applies. - Ping time

Calculate theoretical ping time between Orlando and Shenzhen which is 14102 km distant. Ping time measures the round-trip time for small messages sent from the origin to a destination that is echoed back to the source. The name comes from active sonar ter - Pascal's law

Please calculate according to Pascal's law. Krupp's machines were known for their large size. In 1861, a blacksmith's steam hydraulic press was put into operation in Essen. What was the cross-sectional area of the larger piston if a compressive force of 1 - Amazing number

An amazing number is name for such even number, the decomposition product of prime numbers has exactly three not necessarily different factors and the sum of all its divisors is equal to twice that number. Find all amazing numbers. - Two workers

Two workers will do certain work for 12 days. After 8 days of working, was one removed, and then the other finished the job alone in 10 days. For how many days would do this work alone for each worker? - Bricklayers

8 bricklayers build a house for 630 days. How many bricklayers have to add after 150 days to complete the whole building in (next) 320 days?

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