Statistics Homework Answers & Questions

Waiting for answer There are 200 students in the 7th class at Manchester Middle...
30% 8 students is 4% of 200. So, ##224=18%## play only football, and ##124=8%## play only baseball, and 4% play both . So in total, ##18+4+8=30%## students play a sport (either o...
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Waiting for answer What is the difference between measures of center and measur...
To put it simple, try to capture the nonrandomness of a random variable or population. , on the other hand, try to capture how this process varies.The intuitive notion is quite straightforward so I will give some examples of each. This answer , has a good explanation of measures of center. Th...
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Waiting for answer What does the Empirical Rule (also called the 689599.7 Rul...
It has everything to do with standard deviation ##sigma##, in other words, how much your values are spread around the mean. Say you have a machine that fills kilobags of sugar. The machine does not put exactly 1000 g in every bag. The standard deviation may be in the order of 10 g. Then you can sa...
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Waiting for answer Use the standard normal tables to find ##P(z gt 1.22)##.
P( z 1.22 ) = 1  P( z 1.22 ) By symmetry of the Normal Distribution =1  F( 1.22 ) where F represents the value you look for in the standard normal tables. =1  ( 1  F(1.22) ) Again, by symmetry of N(0,1) =F( 1...
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Waiting for answer What is the mean, median, and mode for 1,2,1,2,1,3,3,4,3?
For such questions, it helps to rewrite the list in order. So: 1,1,1,2,2,3,3,3,4. The mode is the number which appears most often. Since both 1 and 3 appear three times each, the mode is both 1 and 3. The median is the 'middle' number when the list is ranked in order. Since this list has 9 numbers...
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Waiting for answer A spinner has equal sections numbered 18. If you spin the s...
The of the result not being 5 is just one minus the probability of getting a 5 which is ##7/8##. Another way to look at this is that if we know the probability of the result being 5,...
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Waiting for answer What is the differences among p hat, po, and the p value ?
##\hatp## : the estimated value of the parameter ##p## based on your sample. ##\p_0## : the real value of ##p## under the null hypothesis. pvalue : formally, the probability, under the null hypothesis of obtaining the observed value or any other value wich brings more evidence to reject ##H_0##....
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Waiting for answer If you don't know the population standard deviation, can you...
No. You should use student's ttest. I'm assuming the population has a normal distribution. The statistic used in the ztest rely on the population standard deviation, so you should use student's ttest, wich depends on the sample standard deviation instead. The statistic for student's ttest is #...
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Waiting for answer What does it mean if P(AB) = P(A) and P(BA)  P(B)?
This means that the events ##A## and ##B## are independent. ##P(A//B)=P(A)## ##(P(AnnB))/(P(B))=P(A)## ##P(AnnB)=P(A)*P(B)## This is the definition of independence of events ##A##...
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Waiting for answer The heights of young women are approximately normal with mea...
The heights of young women are approximately normal with mean 65 inches and standard deviation 2.5 inches. The heights of men in the same age group have mean (and median) 70 inches. a) What percentage of women are taller than a man of median height? b) What percentage of women are taller than 70 in...
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Waiting for answer How do you find the range and interquartile range for 37, 19...
Range is ##27## and interquartile range is ##17 1/2##. Let us first arrange them in increasing order and data appears as ##10,11,13,19,37## As the range is difference between maxi...
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Waiting for answer What does the RSquared value of a regression refer to?
The Rsquared value of a linear regression is the percentage of variation in your response variable (y) explained by your model. Let us take a dataset with an explanatory variable X...
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Waiting for answer What is the mode, median, and mean of 8, 2, 8, 5, 5, 8?
##8, 6 1/2, 6## Arrange the numbers in order: 2, 5, 5, 8, 8, 8 Mode: 8 (8 occurs the most often) Median: ##(5+8)/2= 6 1/2## (the middle value) Mean : ##("sum")/("number...
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Waiting for answer What is the formula for the chi square test statistic for a...
The formula for the chi square test statistic for a is ##chi2 = Σ [ (Oi  Ei)^2 / (Ei) ]##
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Waiting for answer How many times will EcoR1 cut a random 10kb DNA fragment? Ho...
Here's my initial answer. Requires refining from someone who understands probability better. Each base can be ATCG. (4 possibilities) EcoR1 recognizes a 6bp sequence, which is one out of 4^6 possibilities. So for a 10kb linear fragment, there are (10k5) such possibilities. So number of cuts i...
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Waiting for answer What is the difference between a correlation matrix and a co...
A covariance matrix is a more generalized form of a simple correlation matrix. Correlation is a scaled version of covariance; note that the two parameters always have the same sign (...
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Waiting for answer What is a partition of sums of squares?
SST= SSReg +SSE SST= SSReg +SSE i.e Total sum of squares= Sum of squares due to Regression + Error sum of squares
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Waiting for answer What is the interquartile range of the data set: 9, 30, 2, 4...
Interquartile range is ##46## Interquartile range measures variability, based on difference between third quartile and first quartile. It is defined as ##Q_3Q_1##. To find first an...
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Waiting for answer What is the difference between the standard deviation and re...
The standard deviation represents the squareroot of the average squared difference between each datum and the mean. The relative standard deviation represents this as a percentage of the mean....
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Waiting for answer Define role of histogram?
To graphically Summarize the distribution of a Univariate data set. graphically shows the following: center (the location) of the data; spread (the scale) of the data; skewness...
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