The ages, in years, of 5 boys are 5, 6, 6, 8 and 10. Calculate, correct to one decimal place, the standard deviation of their ages.
-
A.
3.2 years -
B.
2.6 years -
C.
1.9 years -
D.
1.8 years
Correct Answer: Option D
Explanation
| (x) | 5 | 6 | 6 | 8 | 10 | Total |
| (x – bar{x}) | -2 | -1 | -1 | 1 | 3 | |
| ((x – bar{x})^{2}) | 4 | 1 | 1 | 1 | 9 | 16 |
Mean ((bar{x})) = (frac{5 + 6 + 6 + 8 + 10}{5} )
= (frac{35}{5} = 7)
(SD = sqrt{frac{sum (x – bar{x})^{2}}{n}})
= (sqrt{frac{16}{5}} )
= (sqrt{3.2})
(approxeq 1.8 years)