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SandeepReddy
 one year ago
Best ResponseYou've already chosen the best response.0Its taking time for me, Sorry 'bout that

calmat01
 one year ago
Best ResponseYou've already chosen the best response.0Sorry, statistics is out of my area...

calmat01
 one year ago
Best ResponseYou've already chosen the best response.0Yoou should probably try the statistics section.

SandeepReddy
 one year ago
Best ResponseYou've already chosen the best response.0it was long ago that i studied stats, try in statistics section

yashar806
 one year ago
Best ResponseYou've already chosen the best response.0nobody helps me in statistics section

wio
 one year ago
Best ResponseYou've already chosen the best response.0The average should be just (0.15) * 235

SandeepReddy
 one year ago
Best ResponseYou've already chosen the best response.0@wio 15% of the PEOPLE are lefties, not 15% of the seats

wio
 one year ago
Best ResponseYou've already chosen the best response.0\[ n = 205 \text{ trials (number of students)}\\ p = 0.15 \text{ probability}\\ \\ \mu = np \text{ mean}\\ \sigma =\sqrt{np(1p)} \text{ standard deviation} \]

yashar806
 one year ago
Best ResponseYou've already chosen the best response.0what about the second one

wio
 one year ago
Best ResponseYou've already chosen the best response.0As I said before \(n\) is number of students. \(X\) is number of lefties.

satellite73
 one year ago
Best ResponseYou've already chosen the best response.0isn't the mean just 15% of 205 ?

satellite73
 one year ago
Best ResponseYou've already chosen the best response.0yeah i am pretty sure that is what it is. i don't really know any statistics

satellite73
 one year ago
Best ResponseYou've already chosen the best response.0oh i didn't look @wio wrote the answer above

yashar806
 one year ago
Best ResponseYou've already chosen the best response.0so how should I find it

satellite73
 one year ago
Best ResponseYou've already chosen the best response.0find the mean? it is \(.15\times 205=30.75\)

satellite73
 one year ago
Best ResponseYou've already chosen the best response.0standard deviation is what @wio wrote as well

yashar806
 one year ago
Best ResponseYou've already chosen the best response.0I don't understand last one

satellite73
 one year ago
Best ResponseYou've already chosen the best response.0i guess you are to assume that it is normally distributed, so using a normal table find the probability that \(X<27\)

yashar806
 one year ago
Best ResponseYou've already chosen the best response.0in this case should I use 235 or 205 ? for total?

satellite73
 one year ago
Best ResponseYou've already chosen the best response.0or rather change to a z score, that is my guess

satellite73
 one year ago
Best ResponseYou've already chosen the best response.0the 235 is not important. there are 205 students, the mean is \(30.75\) and the standard deviation is about \(5.11\)

satellite73
 one year ago
Best ResponseYou've already chosen the best response.0\(30.7527=3.25\) and \(3.25\div 5.11=.636\) approximately, so find the probability using a normal table that \(X<.636\)

satellite73
 one year ago
Best ResponseYou've already chosen the best response.0that is my guess anyway, i would not bet any money on it

yashar806
 one year ago
Best ResponseYou've already chosen the best response.0i need to use that formula

satellite73
 one year ago
Best ResponseYou've already chosen the best response.0i have no idea what p hat means

yashar806
 one year ago
Best ResponseYou've already chosen the best response.0so for the n should I use 205?

satellite73
 one year ago
Best ResponseYou've already chosen the best response.0yes that is \(n\) but i have no idea what p hat means, so i am useless at this point

yashar806
 one year ago
Best ResponseYou've already chosen the best response.0p hat actually equals to = x/n

yashar806
 one year ago
Best ResponseYou've already chosen the best response.0I dont understand b first question also c

LikeLightning
 one year ago
Best ResponseYou've already chosen the best response.0This is a problem where one can apply the binomial distribution. \[f(k) = \frac{n!}{k!(nk)!} p^{k} (1p)^{nk}\] This is for when there are number of yes/no outcomes. If one yes has probability p for an individual outcome, this formula gives the probability of getting k yes outcomes out of n total outcomes. In this case p would be the probability of a single student being left handed. Now if k students are left handed, the proportion of left handed students is (let's call it y) \[y = k/n\] So what are the mean and variance of this? well to find the mean of the binomial distribution (the mean value of the number of students who are left handed) we'd do \[E[X] =\sum_k k f(k)\] But now we have some proportion k/n, but the probability is the same, f(k) \[E[X/n] =\sum_k \frac{k}{n} f(k) = \frac{1}{n}\sum_k k f(k) = \frac{1}{n}E[X] \]

yashar806
 one year ago
Best ResponseYou've already chosen the best response.0actaully for the second one we have to use p hat

LikeLightning
 one year ago
Best ResponseYou've already chosen the best response.0\[\hat{p} = X/n\] Where X i the number of lefties and n is the total number of students in the class.

yashar806
 one year ago
Best ResponseYou've already chosen the best response.0can you give me a number? i mean use b as an example?

yashar806
 one year ago
Best ResponseYou've already chosen the best response.0cuz i dont really know how to find it ?

LikeLightning
 one year ago
Best ResponseYou've already chosen the best response.0p hat and X are not the usual kind numbers. They are labels to represent a number which has different probabilities for different values.

LikeLightning
 one year ago
Best ResponseYou've already chosen the best response.0For example X = k has the probability f(k) which I gave.

yashar806
 one year ago
Best ResponseYou've already chosen the best response.0so you mean 27 / 205 ?

yashar806
 one year ago
Best ResponseYou've already chosen the best response.0did you see question b ?

yashar806
 one year ago
Best ResponseYou've already chosen the best response.0it asks for mean and standard deviation

bynowSPAMER
 one year ago
Best ResponseYou've already chosen the best response.0In statistics and probability theory, standard deviation (represented by the symbol sigma, σ) shows how much variation or "dispersion" exists from the average (mean), or expected value. A low standard deviation indicates that the data points tend to be very close to the mean; high standard deviation indicates that the data points are spread out over a large range of values. The standard deviation of a random variable, statistical population, data set, or probability distribution is the square root of its variance. It is algebraically simpler though practically less robust than the average absolute deviation.[1][2] A useful property of standard deviation is that, unlike variance, it is expressed in the same units as the data. Note, however, that for measurements with percentage as unit, the standard deviation will have percentage points as unit. In addition to expressing the variability of a population, standard deviation is commonly used to measure confidence in statistical conclusions. For example, the margin of error in polling data is determined by calculating the expected standard deviation in the results if the same poll were to be conducted multiple times. The reported margin of error is typically about twice the standard deviation – the radius of a 95 percent confidence interval. In science, researchers commonly report the standard deviation of experimental data, and only effects that fall far outside the range of standard deviation are considered statistically significant – normal random error or variation in the measurements is in this way distinguished from causal variation. Standard deviation is also important in finance, where the standard deviation on the rate of return on an investment is a measure of the volatility of the investment. When only a sample of data from a population is available, the population standard deviation can be estimated by a modified quantity called the sample standard deviation.

LikeLightning
 one year ago
Best ResponseYou've already chosen the best response.0No, I did not mean 27/205. By X I did not mean the number of seats for left handed people. I meant the number of left handed people. There are different probabilities for different numbers of left handed people.

yashar806
 one year ago
Best ResponseYou've already chosen the best response.0can you solve it ? cuz i cant
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