expected value (mean of X)
1
Standard deviation: 1. Over many repetitions, X averages about 1 per trial.
Steps
- 1.multiply each outcome by its probability: (0)(0.4) + (1)(0.3) + (2)(0.2) + (3)(0.1)
- 2.mean = 0 + 0.3 + 0.4 + 0.3 = 1
- 3.squared deviations times probability: (0 - 1)^2(0.4) + (1 - 1)^2(0.3) + (2 - 1)^2(0.2) + (3 - 1)^2(0.1)
- 4.variance = 1
- 5.standard deviation = sqrt(1) = 1