Question

Suppose the profit a honda dealership makes on the next 5 accords it sells are:564, 1,000, 848, 1,495, 1,348. calculate the standard deviation of the sample. (please express your answer using 2 decimal places)

Answer 1

First we have to find the mean (average)
mean = (564 + 1000 + 848 + 1495 + 1348) / 5 = 5255 / 5 = 1051

now we subtract the mean from every data point, then square it
564 - 1051 = -487......-487^2 = 237169
1000 - 1051 = -51......-51^2 = 2601
848 - 1051 = -203......-203^2 = 41209
1495 - 1051 = 444......444^2 = 197136
1348 - 1051 = 297......297^2 = 88209

now find the mean of the results.....but know when ur dealing with a sample instead of the whole population, u divide by 1 number less...so instead of dividing by 5, u divide by 4.
(237169 + 2601 + 41209 + 197136 + 88209) / 4 = 566324 / 4 = 
141581.....this is called ur variance

now take the square root of the variance and u have ur standard deviation
sqrt (141581) = 376.272 rounds to 376.27 <==