Percent practice

Percentage is a way of expressing a number, especially a ratio, as a fraction of 100. See also our verbal problems in percent or
examples1, examples2, examples3, examples4, examples5.

Calculate:

The number of examples:
Range of values:
Complexity:

10%	of	100	=
50%	of	90	=
20%	of	45	=
60%	of	100	=
20%	of	20	=
20%	of	95	=
20%	of	40	=
90%	of	60	=
20%	of	30	=
90%	of	90	=

Percentage in word math problems

• Built-up area
  John build-up area 4.3 x 6.3 = 27.09 m² with building with a wall thickness 25 cm. How many centimeters would he have to subtract from the thickness of the walls that the built-up area fell by 5%?
• Road
  The angle of a straight road is approximately 12 degrees. Determine the percentage of this road.
• Insurance
  The house owner is insured against natural disasters and pays 0.05% annually of the value of the house 88 Eur. Calculate the value of the house. Calculate the probability of disaster if you know that 50% of the insurance is to pay damages.
• Discounts on rail (ZSSK)
  The railway company ZSSK offers a discount of 40% (SENIOR RAILPLUS) for 9.9 Eur/year. Calculate the real discount rate as a percentage, where passengers will travel 5 Eur per week.
• Human buying irrationality
  I longer watch processors for Socket A on the secondhand market, Athlon XP 1.86GHz with a PR rating of 2500+ costs $7, and Athlon XP 2.16Ghz with a PR rating of 3000+ currently costs $16. Calculate: About what percentage of the Athlon XP 2.16Ghz is more p
• Promile
  Calculate the 17.6 ‰ of 353.
• Iron
  Iron ore contains 61% iron. How much iron ore is needed to produce 29 tons of iron?
• Event probability
  The probability of event N in 5 independent experiments is 0.4. What is the probability that the event N occurs in one experiment (chance is the same)?
• Cone and cube
  About what percentage has cone with base radius r larger volume than a same high cube with square base with edge length r?
• Rectangles
  How many rectangles with an area of 8855 cm² have sides that are natural numbers?
• Date game
  Let now is Tuesday. What day is after 229 days? Write the result as a number: 1=Monday, 2=Tuesday, 3=Wednesday, 4=Thursday, 5=Friday, 6=Saturday, 7=Sunday.
• Web server
  Calculate how many average minutes the web server is unavailable a year if the availability is 99%.
• Rectangle
  In a rectangle with sides 8 and 9, a diagonal is drawn. What is the probability that a randomly selected point inside the rectangle is closer to the diagonal than to any side of the rectangle?
• Sea water
  Seawater contains about 6.5% salt. How many dm³ of distilled water must we pour into 21 dm³ of seawater to get water with 1.2% salt?
• Sea water
  Mixing 63 kg of seawater with 43 kg of rainwater produces water containing 2.7% salt. What percentage of salt does the seawater contain?

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