What is Percent: Definition and 231 Discussions

In mathematics, a percentage (from Latin per centum "by a hundred") is a number or ratio expressed as a fraction of 100. It is often denoted using the percent sign, "%", although the abbreviations "pct.", "pct" and sometimes "pc" are also used. A percentage is a dimensionless number (pure number); it has no unit of measurement.

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  1. S

    How Do You Calculate the Percent Change in Momentum for a Lorry?

    % Change in Momentum [b]1. I do not understand how to do this question as part of my revision. can anyone help? ''Calculate the % change in the momentum of the lorry from loaded to unloaded whilst traveling at a constant velocity of 13.41m/s'' [b]2. Momentum = mass x velocity? Loaded...
  2. F

    Calculating Benzoic Acid Moles & Percent Purity

    chem question please help Homework Statement Ok, so there's .9734 g sample which contained monoprotic benzoic acid C6H5COOH and it's dissolved in 75 mL of water and titrated to the equivalence point with 31.78 mL of .09251 M NaOH solution. a) how many moles of benzoic acid were titrated b)...
  3. A

    Chemistry problem, calculate percent ionization

    acetic acid is a weak acid that ionizes in solution as follows CH3COOH--->CH3COO- + H+ if the freezing point of a .106 m CH3COOH solution is -.203 celcius, calculate the percent of the acid that has undergone ionization. here's what i did, i took .203 celcius=i)1.86 celcius/m (.106m)...
  4. G

    Calculate Percent Dissociation of HBrO

    Here is what should be an easy problem that I am somehow messing up Homework Statement Calculate the percent dissociation of 0.063 M Hydrobromous acid, HBrO. Do not solve the quadratic equation even if the percent dissociation is high. Homework Equations The Attempt at a...
  5. F

    Calculating Percent Uncertainty of Circle Area w/ Radius 1.8x10^4 cm

    Homework Statement What is the percent uncertainty in the area of a circle whose raduis is 1.8 x 10^4 cm? Homework Equations I calculated A=Pi x r^2 = 1017876020 After that, I am lost... The Attempt at a Solution Thanks!
  6. B

    What is the percent of energy lost in an inelastic collision?

    percent of energy lost? I'm confused... I have a case where block 1 moves with certain velocity, hits block 2 (that is at rest) and sticks to it - inelastic collision. Now, the problem is that I have to find the percent of energy (kinetic) that the first block has lost. I know that the...
  7. R

    Simple Q: Percent Disagreement

    Ok, I'm doing my Physics lab and I was told to give a "percent disagreement" if any.. I know it's a very simple question, but I want to make sure if I understood it right... So say I get an expected value to be .541 and when I calculated it, the answer is .715... so is the "percent...
  8. Evo

    Tonight's Full Moon 12 Percent Bigger

    Worth taking a look at tonight. "Tonight's full Moon will be almost 12 percent bigger than some of the full Moons this year, according to NASA, setting up a fine viewing opportunity when it rises in the evening. The reason: The Moon is near perigee, the point on its slightly out-of-round...
  9. N

    Java Discount.java:119: variable percent might not have been initialized

    When I compile this program I get the following error message: Discount.java:119: variable percent might not have been initialized System.out.print("You'll get a " + percent + " discount on "); ^ WHAT THE HELL AM I DOING WRONG? :cry: :cry...
  10. R

    Weight combination by percent

    How on Earth do you do this? What percent by weight of Na2S2O3 is Sodium (Na)? (Na, 23; S, 32; 0, 16) Okay that looks confusing but. The "Na2S2O3" isn't suppose to be spelled like that. It's Na (then a 2 that is haflway beneath the number) And then you repeat with S (lower 2), O and lower...
  11. 0TheSwerve0

    What is the Percentage of Sexual Offenders in the Total Population?

    I've heard a lot about the types of people who are sexual offenders, but how much of the population do they comprise? Not just the correctional population, I mean the total population of residents. I don't know where to find this, and am unsure if it can be found since (as far as I have read)...
  12. B

    Chemistry Calculating the Percent of Cytosine in a DNA Molecule with 28% Thymine

    If a DNA molecule containes 28% thymine, what percent of it will be cytosine? will it be 72%? please help, thank you
  13. A

    Help with percent concentration of hydrogen peroxide if diluted?

    :frown: I did an experiment on the effect of substrate concentration on the rate of a catalase. I was given 6% substrate concentration of hydrogen peroxide. We had to do 3 trials with different concentrations of the hydrogen peroxide but we had to dilute the peroxide ourselves in the second...
  14. S

    Factor(s) that affect percent yield

    Hi everyone, For a science lab, I am asked to find the following: What factor(s) affect percent yield in a reaction which produces calcium carbonate? We are given a selection of chemicals to use to get the CaCl_2 but I have chosen the following: CaCl_2 + Na_2CO_3 --> CaCO_3 + 2NaCl...
  15. T

    What is the correct way to calculate percent increase in math problems?

    Can someone explain to me the following: If a number increases from 108,7 to 113,7 how much in percent has it increased? First I tried to do 108,7 / 113,7 = 0,956. 1 - 0,956 = 0,0439. In other words, an increase of 4,39%. This turns out to be wrong. 113,7 / 108,7 = 1,0459 -> an increase of...
  16. L

    Calculating Percent Change in Kinetic Energy with Varying Force Angles

    % change in KE A sled is being pulled across a horizontal patch of snow. Friction is negligible. The pulling force points in the same direction as the sled's displacement, which is along the +x axis. As a result, the kinetic energy of the sled increases by 36.7%. By what percentage would the...
  17. B

    Percent Difference w/o A: How to Calculate

    Which is ABS( A - B) / A * 100% = ANS Anyway to do it without A? My proff says we should know it or be able to figure it out?
  18. Astronuc

    News Poverty Rate in US Rises to 12.7 Percent

    WASHINGTON (Aug. 30, AP) -- The nation's poverty rate rose to 12.7 percent of the population last year, the fourth consecutive annual increase, the Census Bureau reported Tuesday. The percentage of people without health insurance did not change! Overall, there were 37 million people living...
  19. S

    Percent Uncertainty in Volume of Spherical Beach Ball

    hi didnt know wether to put this in phyics or maths but I am studying for physics so ill put it here. Q: What is the percent uncertainty in the volume of a spherical beach ball whos radius is r = 2.86 +or-0.08m? A: V= 4/3 pie r^3 V = 4/3 pie(2.94)^3 = 106.4463 V = 4/3 pie(2.86)^3 =...
  20. B

    Need help calculating percent composition

    Hello, I need some help calculating the pecent composition of casien and lactose in milk. I started out with 50ml of nonfat milk, at the end of the experiment I got 1.599g casien and 1.610g of lactose. My idea was to convert these values into ml using density but I could not find the...
  21. F

    Measuring Percent of Grade: How to Determine 5% Grade

    I hope a message board of this caliber can help me. Here is my problem. How does one measure a percent of grade? Specifically in a ratio or in a liner measurement how would I know what a 5% grade is? I need to ensure a field is within 5%, is that so many inches out of level in a foot, yard...
  22. M

    Percent Abundance of Br-81 in Bromine

    Br consists of Br-79 and Br-81. The atomic mass of Br is 79.9. Find the % of Br-81 in bromine.
  23. dduardo

    Percent Error When Measured Value is 0 - Always 100%

    How do you get the percent error when the accepted value is very small and the measured value is 0? No matter what the accepted value is if the measured value is 0 the percent error is always 100% based on the formula: (|accepted-measured|/|accepted|)*100%
  24. B

    Percent Abundace Calc Error

    % Abundace Calc Error here's the prob and my work can anyone help me figure out where I'm going wrong? thanks The element silver has two naturally occurring isotopes with masses of 106.91 amu and 108.90 amu. What would be the percent abundance of the first isotope, if the atomic weight were...
  25. M

    Calculating Percent Uncertainty for Volume of a Beach Ball

    hi, I'm attempting a physics problem... it is: What, roughly, is the percent uncertainty in the volume of a spherical beach ball whose radius is r= 2.86 plus or minus 0.09 m. Now, I tried to find the percent uncertainty by just doing .09/2.86, but I'm assuming I need to do something with the...
  26. O

    Solve Percent Problem: Apples Bought & Sold, Can You Help?

    A fruit dealer bought apples at 18 cents a dozen. He sold 80% of them at the rate of 2 for 5 cents and the remainder at the rate of 5 for 2 cents, gaining 58 cents on the transaction. How many apples did he buy ? Can you give me some hints please ? Thanks
  27. A

    Percent Uncertainty of a spherical beach ball

    Question is : What is the percent uncertainty in the volume of a spherical beach ball whose radius is r = 3.86 ± 0.08 m ? The answer is 6 % , but I am not getting that, I am pretty sure I am on the right path, I found the volume of the ball using V = (4 x 3.14 x r^3) / 3 Btw, I am pretty...
  28. A

    Percent uncertainty in the volume of a spherical beach ball

    Question is : What is the percent uncertainty in the volume of a spherical beach ball whose radius is r = 3.86 ± 0.08 m ? The answer is 6 % , but I am not getting that, I am pretty sure I am on the right path, I found the volume of the ball using V = (4 x 3.14 x r^3) / 3 Btw, I am pretty...
  29. W

    Why can't machines be 100 percent efficient?

    Why can't machines be 100 percent efficent[?]
  30. I

    Calculating Percent Acetic Acid by Weight in Vinegar: A Simple Guide

    The molarity and percent by weight of the acetic acid in the vinegar. Use a value of 1.005 g/mL for the density of the vinegar. Acetic acid molarity in vinegar = .208 mol / L How do you calculate the Percent acetic acid by weight (using the acetic acid molarity)? Thanks for the help.
  31. Ivan Seeking

    96 percent of cosmos puzzles astronomers

    http://www.cnn.com/2003/TECH/space/06/20/dark.energy.ap/index.html
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