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basic statistic questions.. please help (1 Viewer)

nevereddy

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Note: most are multiple choice/true or false and are only 9 questions.. so dont be afraid.. LOL
i really need help from u guys, as i thought i was on the right track with my statistic course, but ended up getting like 4 or so wrong answers..
anyways, could u please check my answers... or provide ur own answers..

1. A sample of 9 students is selected and their quiz marks out of 10 recorded as: 0, 3, 1, 7, 5, 7, 6, 7, 9. The median mark is less than the mean mark.
(true or false)-- i got false..

2.When extreme values or "outliers" are present in a set of data, which of the following descriptive summary measures are the most appropriate to use?
a)Median and standard deviation,
b)mean and standard deviation,
c)variance and range
d) interquartile range and median
i got b

3.Consider a sample of size n=10 where the sample mean is 8 and sample variance is 16. Consider a second sample that is exactly the same as the first except that there is an additional observation that takes on the value of 8. What is the sample variance for this larger sample with n=11 observations? (Your answer should be correct to one decimal place.)
im not sure.. please answer..

4.A GP samples 5 of her patients and collects information on the number of visits to the GP in the last year and the age of the patient. The 5 (visit, age) pairs of observations are given as:
(0, 20), (0, 20), (2, 40), (2, 50), ( 2, 70)
i got 20.. please check

5. What is the sample correlation between two variables if the covariance is 7 and the two sample variances are 4 and 25? (Your answer should be correct ot one decimal place.)
0.07 or 0.1

6.In a study of the impact of age on the number of GP visits, the covariance between age and GP visits is found to be positive. This implies that the line of best fit will have a positive slope coefficient.
true or false.. i got false

7.For a sample of 100 students the sample standard deviation for their heights measured in centimeters is found to be 8. If these heights were coverted in meters, what would be the sample standard deviation? (Your answer should be correct to two decimal places.)
my answer is 0.08...

8.What is the lower quartile if the upper quartile is 16 and the interquartile range is 4? i got 12..

9. Suppose a telemarketing firm uses a device that randomly dials residential telephone numbers in a particular city. Of the first 100 numbers called, 43 were not listed in the telephone book. This is not surprising, because 52% of all residential phones in this city have unlisted numbers. In this example, 52% is a population parameter and 43 is a sample statistic.
true or false .. i got false..
 

deterministic

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I will only do the ones which are incorrect or unknown.

2. The mean is very dependent on outliers and can change significantly due to one very large/small value. Thus it doesn't give a good summary of the WHOLE data. The median on the other hand is independent of outliers , and hence would give a much better summary of the data. Likewise interquartile range is not sensitive to outliers so hence it is good. So d) is the correct answer.

3. Sample variance =
So with ten data pts, we have . Using 11th data pt: Variance =


4. What are you trying to find??

5.
 
Last edited:

nevereddy

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um.. sorry .. :spin:

number 4. find the sample covariance..
anyways i got 20, but im doubting my answer.

also, ive been askin around.. and im gettin mixed answers for 6 and 9...

for 9.. im pretty sure im correct, but not sure about 6

please help..
 

zehurricane

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why are we doing your homework?

and damn, the questions are bloody easy as..
 

Arceupins

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You're retarded.

I did general maths (band 5) and got 9/10 each time.

That quiz was fucking child's play.
 

davidgoes4wce

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Note: most are multiple choice/true or false and are only 9 questions.. so dont be afraid.. LOL
i really need help from u guys, as i thought i was on the right track with my statistic course, but ended up getting like 4 or so wrong answers..
anyways, could u please check my answers... or provide ur own answers..

1. A sample of 9 students is selected and their quiz marks out of 10 recorded as: 0, 3, 1, 7, 5, 7, 6, 7, 9. The median mark is less than the mean mark.
(true or false)-- i got false..
.
Here is my Excel screenshot. Q1 is False.



I sorted the numbers from smallest to largest and then preceded to calculate the MEAN and MEDIAN, using Excel Commands =MEAN(), and MEDIAN().
 

davidgoes4wce

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7.For a sample of 100 students the sample standard deviation for their heights measured in centimeters is found to be 8. If these heights were coverted in meters, what would be the sample standard deviation? (Your answer should be correct to two decimal places.)
my answer is 0.08...
.


 

davidgoes4wce

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4.A GP samples 5 of her patients and collects information on the number of visits to the GP in the last year and the age of the patient. The 5 (visit, age) pairs of observations are given as:
(0, 20), (0, 20), (2, 40), (2, 50), ( 2, 70)
i got 20.. please check

..

Here is the solution to Question 4, I can confirm your value of 20 is correct.

 

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