In: Finance
A stock had returns of 8 percent, –8 percent, 3 percent, and 14 percent over the past 4 years. What is the standard deviation of this stock for the past four years?
Multiple choice
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Option (c) is correct
First we will calculate the Arithmetic mean return as per below:
Formula for Arithmetic Mean is:
Arithmetic Mean (AM) return = Sum of returns / No. of returns
Sum of the returns = 8 + (-8) + 3 + 14 = 17
No. of data = 4
Arithmetic Mean return = 17 / 4 = 4.25
Steps for calculating standard deviation are:
First we will calculate the deviation of returns from the mean return value as per below:
1st: 8 - 4.25 = 3.75
2nd : - 8 - 4.25 = -12.25
3rd: 3 - 4.25 = -1.25
4th: 14 - 4.25 = 9.75
In the next step, we will square the deviations computed above, as per below:
1st: (3.75)2 = 14.0625
2nd : (-12.25)2 = 150.0625
3rd: (-1.25) = 1.5625
4th: (9.75)2 = 95.0625
In the next step we will add up the values calculated above:
Sum of squared deviations = 14.0625 + 150.0625 + 1.5625 + 95.0625 = 260.75
In the next step we will calculate the variance by the following formula:
Variance = Sum of squared deviations / N- 1
where, N is the no. of data, which is 4 here.
Putting the values in the above equation, we get,
Variance = 260.75 / 4 -1
Variance = 260.75 / 3 = 86.92
In the final step, we will square root the variance calculated above to find the standard deviation:
Standard deviation = (86.92)1/2 = 9.3