Which of the values below is impossible for the descriptive measure in question?

Question

Which of the values below is impossible for the descriptive measure in question?
Answer
r = 1.25
mean = -0.2
s = 3.4
both (a) and (b)
both (a) and (c)
Here are the number of hours that each of a group of students studied for this exam:

2 4 22 6 1 4 1 5 7 4

What is the standard deviation of the number of study hours? Answer 5.8 6.1 37.2 33.4 56 After finding the mean I then found the sum of all numbers divided that by the numbers minus one and got 6.09 which is 6.1 rounded up. Is this correct?
Which of the values below is impossible for the descriptive measure in question?
Answer
r = 1.25
mean = -0.2
s = 3.4
both (a) and (b)
both (a) and (c)
Here are the number of hours that each of a group of students studied for this exam:

2 4 22 6 1 4 1 5 7 4

What is the standard deviation of the number of study hours? Answer 5.8 6.1 37.2 33.4 56 Here are the number of hours that each of a group of students studied for this exam:

2 4 22 6 1 4 1 5 7 4

What is the standard deviation of the number of study hours? Here are the number of hours that each of a group of students studied for this exam:

2 4 22 6 1 4 1 5 7 4

What is the standard deviation of the number of study hours? 5.8 6.1 37.2 33.4 56 After finding the mean I then found the sum of all numbers divided that by the numbers minus one and got 6.09 which is 6.1 rounded up. Is this correct? 5.8 6.1 37.2 33.4 56

Explanation / Answer

Now, expected value of x (x represents each student with a distinct number of study hours. Since each student has different study hours thereby, it has the value of 1 in each case) is represented by E(x) E(x) = 2x1+4x1+22x1+6x1+1x1+4x1+1x1+5x1+7x1+4x1=56 and E(x2) = 2x12+4x12+22x12+6x12+1x12+4x12+1x12+5x12+7x12+4x12=56 Now, E(x)2 - E(x2) = 562-56= 3080 Variance = 3080 Standard deviation = variance1/2 = 56 (approximately) Thus the correct option is (e) 56

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