# Percentages + third power - practice problems

#### Number of problems found: 24

- The power generator

How much would be paid for the generator if it costs 2000 and 12.5% tax is charged on it? - Electric cooker

During which time t does an electric cooker with power input P = 500 W and with efficiency n = 75% heat water with mass m = 2 kg and temperature t1 = 10°C to the boiling point (t2 = 100°C). The specific heat capacity of water is c = 4 180 J. Kg-1. K-1 - The ball

The ball has a radius of 2m. What percentage of the surface and volume is another sphere whose radius is 20% larger? - Power input

The construction lift lifted a load weighing 300 kg to a height of 12 m with a uniform movement. How long has it taken for the load to be lifted if the efficiency is 75% and the engine has a power input of 5 kW? - Helmet

Nowadays cycling better results could be obtained not only due to rider physical preparation but also thanks to using updated technologies. One of the essential parts of the rider´s equipment is his or her helmet. While most bikers wear a helmet mainly to - Precious metals

In 2006-2009, the value of precious metals changed rapidly. The data in the following table represent the total rate of return (in percentage) for platinum, gold, and silver from 2006 through 2009: Year Platinum Gold Silver 2009 62.7 25.0 56.8 2008 -41.3 - Pyramid cut

We cut the regular square pyramid with a parallel plane to the two parts (see figure). The volume of the smaller pyramid is 20% of the volume of the original one. The bottom of the base of the smaller pyramid has a content of 10 cm². Find the area of the - Performance

Two masons with the same performance would have been made of plaster for six days. One of them, however, has increased its daily performance by 50%. How long would it take them now to make plaster together? - Cube edges

If the edge length of the cube increases by 50%, how does the volume of this cube increase? - Volume and body diagonal

Calculate how much the volume and body diagonal of the cuboid decrease if we reduce each of its three edges a, b, c by 18%? - Find the

Find the number x, which if it increases by 2, then its square increases by 21 percent. - Rate or interest

At what rate percent will Rs.2000 amount to Rs.2315.25 in 3 years at compound interest? - Job task

After two hours and 40 minutes, the job is finished. Compared to last year, we were 40 minutes faster. What is the percentage increase to our performance? - Efficiency

What is the power output of a kettle 2 kW with an efficiency of 90%? - Square

Suppose the square's sides' length decreases by a 25% decrease in the content area of 28 cm². Determine the side length of the original square. - Lathe

Calculate the percentage of waste if the cube with 53 cm long edge is lathed to cylinder with a maximum volume. - Elevator

In homes with more floor elevators are used. For passenger transport, the most commonly used traction elevator counterweight. The top of the shaft engine room with the engine. The car is suspended on a rope, which is guided up over two pulleys to the coun - Sale

If the product twice price cut by 25%, what percentage was price cut in total? - Efficiency

A certain device consumes 28 kW and delivers 14 kW. Find its efficiency. - Lathe

From the cube of edge, 37 cm was a lathed maximum cylinder. What percentage of the cube is left as waste after lathed?

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