In: Statistics and Probability
On the midnight shift,
the number of patients with head trauma in an emergency room has
the probability distribution shown below.
x | 0 | 1 | 2 | 3 | 4 | 5 | Total |
P(x) | .09 | .32 | .27 | .17 | .11 | .04 | 1.00 |
(a) Calculate the mean and standard deviation.
(Round your mean value to 2 decimal places and standard
deviation to 3 decimal places.)
Solution:
x | P(x) | x * P(x) | x2 * P(x) |
0 | 0.09 | 0 | 0 |
1 | 0.32 | 0.32 | 0.32 |
2 | 0.27 | 0.54 | 1.08 |
3 | 0.17 | 0.51 | 1.53 |
4 | 0.11 | 0.44 | 1.76 |
5 | 0.04 | 0.2 | 1 |
Sum | 1 | 2.01 | 5.69 |
Mean = X * P(X)
= 2.01
Standard deviation =
=X 2 * P(X) - 2
= 5.69 - (2.01)2 = 1.6499
Standard deviation = = 1.284