Percentages + power - math problems

Number of problems found: 22

Efficiency
What is the power output of kettle 2 kW with efficiency 90%?
Sphere fall
How many percent fall volume of a sphere if diameter decrease 3×?
Rate or interest
At what rate percent will Rs.2000 amount to Rs.2315.25 in 3 years at compound interest?
Efficiency
A certain device consumes 28 kW and delivers 14 kW. Find its efficiency.
Cube edges
If the edge length of the cube increases by 50%, how does the volume of this cube increase?
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
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?
Find the
Find the number x, which if it increases by 2, then its square increases by 21 percent.
Lathe
Calculate the percentage of waste if the cube with 53 cm long edge is lathed to cylinder with a maximum volume.
Cube in ball
Cube is inscribed into the sphere of radius 181 dm. How many percent is the volume of cube of the volume of the sphere?
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?
Lathe
From the cube of edge, 37 cm was a lathed maximum cylinder. What percentage of the cube is left as waste after lathed?
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%?
Cube zoom
How many percents do we increase the volume and surface of the cube if we magnify its edge by 38 %?
The ball
The ball has a radius of 2m. What percentage of the surface and volume is another sphere whose radius is 20% larger?
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.
Performance
Two masons with the same performance would have made of plaster for 6 days. One of them, however, has increased its daily performance by 50%. How long would take they now to make plaster together?
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
Computer revolution
When we started playing with computers, the first processor, which I remember was the Intel 8080 from 1974, with the performance of 0.5 MIPS. Calculate how much percent a year rose CPU performance when Intel 486DX from 1992 has 54 MIPS. What wou