# 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. ### B Equation to approximate percent likelyhood of different sigma events

Hi! I was wondering if there was an equation to plug in a standard deviation value and get back approximately the percent likely hood of getting that sigma (for example 1 sigma would be 33%, 3 sigma 0.27%, etc). Just something that approximates it with algebra, no calculus Thanks!
2. ### Interpreting Statistical Questions: Ice Hockey Player Diff.

The solution in my book: 5/4 = 1.25. That is 25 % more. What I came up with: I thought that now we have totally 9 players. So A: 4/9 and B: 5/9. The difference is 1/9 which is about 11%! A friend told me : The difference between B & A is 5-4=1 The changing rate is (5-4)/5 = 0.2 ! So B has 20...
3. ### Engineering Calculating the percent composition of weight of an alloy

I found the density of carbon and iron: ρ_fe=7.87 g/〖cm〗^3 ρ_c=2.26 g/〖cm〗^3 Using equation 2: atom density of iron and carbon N_fe = 8.48e22 cm^-3 N_c = 1.13e23 cm^-3 Using equation 1: macroscopic scatter and absorption cross sections of iron and carbon Σ_a,fe = .217 cm^-1...
4. ### Chemistry Calculating the mass percent from a given volume % and density

[I've solved b, but can't figure out a for the life of me. I have a couple of attempts, but it's just nonsense, it's like I've short circuited.]
5. ### Percent change vs. percent difference

What is the difference between percent change and percent difference? When would you use one over the other? Thanks.
6. ### B What percent of everyday-life electrons are collapsed?

So if particles such as the electrons when "measured" forsake their probabilistic wave form and manifest into a definite particle form, does that mean for all intent and purpose the electrons of every objects we observe are already collapsed? If that's the case how did the labs get pre-collapse...
7. ### Is percent yield based on grams or moles?

Is percent yield based on grams or moles? Thanks.
8. ### Chemistry Molecular percent of compounds

mx remets to mass in gram of the compost x nx remets to moles of the compost x nTot remets to the total moles x remets to the additional moles of D2 I considered the molar mass: MH2 = 2u MHD = 3u MD2 = 4u 10 = mH2 + mHD + mD2 10 = nH2*2 + nHD*3 + nD2*4 10 = nTot + 0.9nTot + 0.8nTot nTot =...
9. ### Finding Percent of Water & Oil in a Mixture from Surface Tension

I was looking for on the internet for a while without a success. If I know that the surface tension of pure oil is ##\gamma_o=A## and I know that the surface tension of pure water is ##\gamma_w=B## so if I have a mixture of water and oil with surface tension ##\gamma_m=C## am I able to know...
10. ### B Normalization versus Percent Change

I have been working with some time series data of spectral signals, each wavelength has a different signal, so I normalize the data so I can plot it effectively. However, I am struggling to quantify the new normalized data. I will give an example below. Normalizing data often refers to...
11. ### Circuits and the percent change of current when the switch is closed

For an ideal battery (r = 0 Ω), closing the switch in (Figure 1)does not affect the brightness of bulb A. In practice, bulb A dims just a little when the switch closes. To see why, assume that the 1.50 V battery has an internal resistance r = 0.30 Ω and that the resistance of a glowing bulb is R...
12. ### Percent Change Of current when the switch is closed

(.174A-.181A)/.181A=-3.86% but it says it wrong, and I did (.181A-.174A)/.174A =4.02% but this was wrong too. I've tried 3.87%,3.86%,-3.87%,-3.67%,4.02%, and -4.02% but all were wrong. I'm really not sure what to do here.
13. ### What percent of the universe is outside of galaxies?

Summary:: What percent of the universe is outside of galaxies? Hello, What percent of the universe is outside of galaxies? I need this information for a writing piece I am doing. I need specifically to be able to state that if someone was to randomly relocate to somewhere else in the...
14. ### Engineering Find out the percent exergy loss

Problem, with state values, and pie chart (Fig 4.20) showing answers: ^ This shows the system in question (Kapitza Liquefaction System). Methane gas enters into the compressor (c), then goes through the first heat exchanger (HX1). Some of it (z) gets routed to the expander (exp). Afterwards...
15. ### Sig figs/certainty in percent error calculation

Hello, all. Quick question about how to apply sig figs in percent error problems. Eg. If the actual/target value is 1.95 g and we measure 1.87 g, then should the percent error of our measurement be reported as 4.10% or 4%? Normally, at least abstracting from the problem, after subtracting...
16. ### What is the Percentage Profit on a House Bought for $500 and Sold for$700?

The house was bought for $500 and sold for$700(700-500=200) 200/500*100%=40%,is the solution right verify please. Thanks,help if incorrect.
17. ### Find the price of the new offer

Attempting: 20% is 2/10 as a fraction. 550: by 10 and *2 =110 Is it correct if not explain to me please Thanks
18. ### Probability question: picking colored marbles out of a bag

there are 5 marbles in a bag: 4 are blue, and 1 is red. Solution there are 5 in total 4 are Blue so 4/5 or80% Is it right? thanks

34. ### Calculating Mass Percent in UO2 Nuclear Fuel

Homework Statement Hello guys, I was using mcnp code SERPENT, and while defining materials i encountered a problem. The problem is that for example: if I'm given that i have a 3.5 percent enriched U-235. how do i find the rest of the mass percents of U-234, U-238, O2. Now since i know mass...
35. ### Expressing concentrations as a percent

You measure the concentration of O2 in seawater to be 5.0 mg O2/L H2O. Express this concentration as a percent. Question 2: The Earth's atmosphere contains 21% O2/L of air. How much more oxygen does the atmosphere hold than seawater from the previous question? So for question one I got 0.01%...
36. ### Find The Percent Change In K.E. Of Rod Hit By Putty

I'm trying to solve this problem, however I'm unsure if my reasoning is correct - I do agree with the answer, but something seems wrong to me in my reasoning. 1. Homework Statement A rod is on a frictionless surface, and is defined by the length L and mass M. It is hit on one end by a piece...
37. ### MHB What percent more is one percentage than another?

Hi all, I'm hoping someone can help me. I'm writing a work report and trying to figure out what % increase there is between one percent and another. The example I have is; 91% of those those who feel part of a community are satisfied with their overall experience, compared to 63% those who...
38. ### I Percent of stars in our galaxy that belong to clusters?

Of all the stars in our galaxy, how much of them belong to clusters?? Is our sun rare in terms of not belonging to any cluster? I can't find any sources on that
39. ### Why is my program not returning a percent?

Homework Statement import java.util.ArrayList; public class Scores { private ArrayList<Integer> examScores = new ArrayList<Integer>(); private int[] howManyScorers; private int accepted; private double acceptedPercent; public Scores(ArrayList<Integer> scores) {...
40. ### Best Method of Analyzing Experimental Percent Error

Homework Statement I have performed a chemistry experiment where I analyzed how the diluting of two reactants with the same volume and initial concentration impacts the percent yield of a precipitate product. Thus my IV was concentration and my DV was percent yield. My question is what is the...
41. ### Given percent composition, find mass per litre of solution

Homework Statement A 15% by mass solution has a density of 1.2 g/mL. What is the mass per liter concentration of this solution? → (a) 180 g/L (this is the answer, pretend you don't know) (b) 150 g/L (c) 125 g/L (d) cannot be determined from this information Homework Equations Density...
42. ### Momentum and percent kinetic energy loss

Homework Statement 1.) A 1200 kg car traveling at 20 m/s collides with a stationary 1400 kg car. The two cars lock together. Determine the speed of the vehicles immediately after the collision if 80% of the initial kinetic energy is converted to heat and sound during the collision 2.) Must all...
43. ### Chemistry Determine Weight Percent given molecular weight....

Homework Statement So for my homework assignment in 'Materials Science and Engineering', We were given the following problem. 1. Li and Ra both are both BCC metals. For this problem assume they form a complete solid solution (even though the very large difference in their atomic size tell us...
44. ### Chemistry What is the percentage of KClO3 in a mixture after removing oxygen?

Homework Statement A 16.00g sample of a mixture of KClO3 and KCl is heated until all the oxgen has been removed from the sample. The product entirely KCl (no O), has a total mass of 9.00g. What is the percentage of KClO3 present in the original mixture? 16.00g mixture 9.00g mixture without...
45. ### Importance of Angle in Light Spectrometry for Reflectance Measurements

Homework Statement Hello, I've been using a light spectrometer to try to measure the reflectance of a sample of a protein I have on a glass slide. I followed the manual's instructions and first took a dark spectrum and a reference spectrum. However, the intensity was too high (far above the...
46. ### Why is Percent Change Calculated Like This?

Homework Statement The formula for price elasticity in my micro/macroeconomics course is: elasticity = For those unable to view the image: (change in quantity / avg quantity)/(change in price / avg price) My question is: Why is it that the average quantity/price is used instead of just the...
47. ### What is the Impact of a Local Tourism Tax on Customer Satisfaction?

Homework Statement a. Lucy's Lunch and Latte has found that customers are put off by the local tourism tax of 9% that is added to their bill. If Lucy decides to cover the tax herself, rather than adding it to the customer's bill, what percent will the customer see in savings? b. Lucy decides...
48. ### Density of Solution and mass percent

There are two numericals, 1. Density of Methanol is 0.793 kg/l. Find molarity. ANSWER is : Desity/ Molar mass = Molarity (UNDERSTANDABLE) In other numerical 2. Concentration of H2SO4 is 98% by mass having density of 1.84gm/ml. Calculate Molarity. here they used another formula. now my...
49. ### Why does flipping the order of numbers in a basic percent problem work?

If I am looking for 88% 50, I can put the percent sign on the other number and flip the order of the numbers: 88% of 50 = 50% of 88 = 44. I can solve this numerically but I don't understand conceptually why this works. Why does this work?
50. ### What Is the Percent Yield from Aluminum to Potassium Alum?

Here is the question: If 75.0 g of potassium alum is obtained from 5.00 g of aluminum, what is the percent yield? This is what I've done so far, but I'm not sure if it is fully correct: 5.00g Al x (1/26.98156) x (1/1) x 258.207 = 47.84882537g potassium alum Wouldn't this then be the...