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Questions tagged [percentile]

A value representing the lowest $n$ percent of the values in a data set or of the possible values of a random variable.

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Empirical Rule percentile?

Back again! This is probably simple, but I also wanted to check my answer, so here is the question: The distribution of heights of adult American men is approximately normal with a mean 69 inches and ...
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11 views

Variation of percentile value of a set of data after normalization

I have a theoretical question. Given a set of data, whose 95th percentile is X: If I normalize the data, doing zscore normalization, i.e. (data-mean)/std, is the 95th percentile of the normalized ...
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41 views

What Conclusions Can I Draw from Percentiles About my Set of Data?

I have a specific survey question that I am analyzing for the topic Should High Schools Implement a Uniform Policy?. I am supposed to create biased survey questions ...
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26 views

Understanding percentile computation

I understand percentile in the context of test scores with many examples (eg. you SAT score falls in the 99th percentile), but I am not sure I understand percentile in the following context and what ...
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60 views

What Can Median Tell Me About my Data?

For a final assignment for math, I was required to take the "Yes!" side of 'Should Uniforms Be Implemented at School?' My job was to create a biased survey that would make people agree with our side ...
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45 views

Can You Have 2 Numerical, Identical Values To Represent the nth Percentile?

For an assignment, I am required to find the value of a piece of data in the 70th percentile using mean and standard deviation. Here is my organized data in ascending order: ...
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Calculate percentile rank

I am confused with the concept of percentile rank. I am in the top 7 of my class, how would I calculate my percentile rank? Number of students 72 I am 7th rank in my class Does this mean my ...
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Conventional notation for quartiles of probability distributions (not quartiles of samples)

EDIT: Should I better post this question in https://stats.stackexchange.com/?? NOTE: Here, I am supposing that the reader knows the difference between population (which is where a probability ...
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Is using PERCENTILE the right way to score these results?

We are trying to score the 911 call center. We have 10 responders. Management wants each call to result in a dispatch in 60 seconds or less. Some responders react within the 60 second goal, some ...
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29 views

Why do we use average of two numbers during calculation of percentile?

Let me give you example: The right answer is supposed to be (according to the book) "908". I see how we arrive to such number.(10*0.4=4, then we take the fourth film from the bottom, it's "Jaws". The ...
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207 views

How to calculate Percentile of given value based on other values and percentile

I have a problem related to a formula and I need help from all of you. It may use some statistics formula to solve the problem. Your help would be appreciated. =========== We have following values (...
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27 views

Slope and Expected Value of Percentile Ranks

Looking for help with this problem: Assume a child's expected income percentile is a linear function of their parents' income percentile. It turns out the intercept is enough to deduce the slope. If ...
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What is standard error (any approximation) in a variable when only Mean value and percentiles (16th and 84th) of the PDF over variable are known?

I have variable 'X' for which I know only the MEAN value along with 16th and 84th percentile of its PDF. Now this variable (X) is used in another variable calculation (let's say 'Y') for which I have ...
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47 views

Calculate the value given several percentiles and their values

On a particular test whose scores are distributed normally, the 2nd percentile is 1,720, while the 84th percentile is 1,990. What score, rounded to the nearest 10, most closely corresponds to the 16th ...
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118 views

Is there something like 700%?

I always see companies advertising their products as "700% effective " or "the product kills 900% germs". But percent means "out of hundred". So how can the percentage be more than 100 like 700% or ...
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The 44th percentile is the .44th __?

I'm searching for a very simple word. We are all familiar with the concept of the 44th percentile of a real, random variable. In a sense, percentile (parameterized by the random variable) is a ...
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How can I calculate desired selling price based on margin? [closed]

I use the following formula to calculate profit margin: $$\text{profit_margin} = \frac{\text{selling_price} - (0.15\cdot \text{selling_price}) - \text{sourcing_cost}}{\text{sourcing_cost}}$$ What ...
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How can 10th (or any other sufficiently low) percentile be equal to the mean number?

For example, a 3rd percentile equal to n means that values of no more than 3% of observations in a group of observations are strictly less than n and that values of no less than 3% of observations are ...
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When do mean value may be equal to some percentile? Let’s say 3rd percentile.

I started reading about statistics recently and saw that this question was asked several times during interviews.
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65 views

Find the limit of a probabilistic matrix

I have the following matrix $M$, where the first column is a score vector and the second column is a vector with the corresponding probabilities: $$ M = \begin{pmatrix} 0 & \psi_0\\ 1 & \psi_1\...
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Piecewise integration: find the 75th percentile of this continuous random variable.

The problem from a quiz of mine is as follows: In general, I know how to find the $p$th percentile of a random variable $X$, given its probability density function $f(x)$. You simply solve for the ...
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106 views

Calculate/infer percentile of a number not in the original data set

Let's say I have a set of any 10 numbers and I've calculated some percentiles for them, e.g. 40th, 45th, 50th. Then I have an 11th number that falls within the minimum and maximum values of the ...
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159 views

Formula to get total number of students from given percentile and rank

I just want to know that how i get total number of student who have given the exam with me if have my rank and percentile of that given exam. Formula to get total number of student who appeared in ...
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57 views

finding out percentiles from given data

I'm trying to improve my understanding of percentiles by just coming up with data of my own and analyzing it (as opposed to just mostly reading 'x' percentile means you performed better than x % of ...
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73 views

How is this statistical index called?

I need to calculate an index that is to be derived like this: If we have some data: 850 700 500 480 300 100 50, we first sort it from the large to small: ...
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87 views

Compute/approximate percentile from percentiles of smaller time windows

As the title says, I am interested in computing or approximating a percentile (e.g. 95%) for a large time interval (e.g., 1h) based on the percentiles of smaller time windows (30s). I am aware that ...
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750 views

Explanation of this percentile GRE problem.

Question: 300 test results are integers ranging from 15 to 75, inclusive. Dominick’s result is clearly in the 80th percentile of those results, not the 79th or the 81st. Quantity A: Number of other ...
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finding the percentiles of a transformed weibull.

assignment question from the textbook please i need help on these question. I was asked to use the data in 102 on the second image i named "question from the textbook" to answer question 1.I have ...
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66 views

Is the third quartile in 13 data the tenth value or the mean of the tenth and eleventh value?

If you have 13 data values written in order and you choose the median as the 7th value, this leaves 6 values on either side of the median. The median of these 6 values is the mean of the two central ...
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74 views

How exactly are quartile and percentile calculated?

I am slightly confused w.r.t. to the exact definitions of quartile and percentile. Considering, a dataset consisting integers 1 to 100, each of which is present exactly once. i.e, the set {1,2,3,4,.....
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50 views

Given the percentage of each range of years, how to calculate the total average of years? [closed]

For example, in a pet shop, 35% of cats is 1 ~ 2 years old, 40% is 2 ~ 4 years old and the remaining 25% is 4 ~ 6 years old. How can I know the average of cat's age in this pet shop? http://i.imgur....
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48 views

Estimating a percentile based on running totals

I want to know of a way to estimate the percentile of potentially highly skewed data where I will not have access to all of the data at once. We can assume that in general, despite the fact that the ...
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853 views

How to solve this question of percentile and percentile groups?

The outcome of a standardized test is an integer between 151 and 200, inclusive. The percentiles of 400 test scores are calculated, and the scores are divided into corresponding percentile groups. ...
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557 views

Correction of -0.5 in percentile formula

My question is about how to calculate the percentile of a list of numbers. I found on the Internet the formula: $$p_i=100·\frac{i-0.5}{N}$$ Nevertheless, I don't understand the reason of -0.5. I ...
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39 views

(Distance measured / height) * 100??? Is this correct?

I have an exercise that tells me to face the wall and bend until my knees touches the wall without lifting my heel, then measure the max distance from my big toe to the wall without my raising my heel....
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33 views

Percentile solving without full data set

Given a group of 245 students taking an exam: Student A scores in the 97th percentile Only 33.88% of students passed the exam Find: Student A's rank among the 245 people I did the math myself ...
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184 views

Percentile Question

Consider a set of starting salaries for engineers: $\$42000,$ $\$43412,$ $\$45500,$ and $\$53750.$ a) what percentile corresponds to a salary of $\$45,500$? b) what salary corresponds to the 50th ...
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Statistics Issue Related to Percentages and Corresponding Z-Scores

I had a disagreement with my professor about this specific problem recently and so I though it would be good to get some other input on the matter. Here's the question: 22% of a population of fish ...
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528 views

95th percentile of average

All is know is that the average of a data set (that i do not know ) is 22,2. And that is 95th percentile is 32,8. Is it possible to calculate its 80th percentile with only this informations ? Thank ...
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Percentiles: $F(x)$ or $\int f(x)$

When solving for percentiles with cdf, Should I discard constants? From my book: $F(x_p) = P(X \le x_p) = \int_{-\infty}^{x_p} f(x) dx = \frac{p}{100}$ If I don't have the cdf formula, I can ...
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694 views

Percentile of sum of random variables

There appears to be some similar questions, e.g., here. However, none got answered. Hence, I would like to ask the following question: Say $X$, $Y$, $Z$ are three random variables (not $i.i.d.$) and $...
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767 views

Calculate the 30th and 60th percentiles of X.

The following function is the CDF of a mixed distribution $$F(x)=\begin{cases} 0,& \text{when }x<0\\ \frac{x+1}{8},&\text{when } 0≤x<1\\ \frac{x+3}{8},&\text{when } 1≤x<3\\ 1,&...
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146 views

Is dividing the median (50th percentile) by 2 an acceptable approximation of the 25th percentile?

So for example, if the median is equal to 0.840335, could I approximate the 25th percentile as $0.840335 / 2 = 0.4201675$? Would this be possible if one assumes the underlying data is normally ...
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9k views

Is $50$th percentile equal to median?

Consider we have the $100$ distinct integers between $1$ and $100$ inclusive. The median and fiftyth percentile can be calculated as below. Ordering: $1,2,3 ..... ,98, 99, 100$ The median is $(50+...
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2k views

Computing reverse percentile

I am actually looking for a way to indicate a certain point on an interpolated curve in a plot (see this question), but judging by the amount of answers there, that's just not possible. So is there ...
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98 views

Finding percentile rank.

The problem goes: Given the following table bellow: \begin{array}{|l|c|c|c|c|c|c|c|c|c|c|} \hline \textbf{Data} & -10 & 25 & 37 & 40 & 43 & 54 & 111 & 113 & ...
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Interpretation 0f percentile

How do we interpret the meaning of a percentile? What I have learned from books is as follows: "If a score is the 40th percentile, this means that it is larger than 40% of the distribution, while ...
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301 views

Compare percentile of two data set

What comes in my mind is- based on starting point of set A and set B, Quantity A and Quantity B can be different. so, answer should be D (The relationship cannot be determined). But, I can't find any ...
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719 views

How to interpret this excel formula for expected loss

P(E) Lo Bnd Uppr Bnd Exp. Loss 0.050 500,000 2,000,000 54,643 0.100 400,000 2,500,000 116,785 I'm looking at a spreadsheet that accompanies the ...
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575 views

Spending and left over amount/percentages

Question 1) Cam would like to spend some of his money on friends. Of the 350 dollar budget he was given, he has to spend 75.00 dollars on office supplies, 10.00 dollars per person for an entrance fee ...