Question

The probability distribution of a random variable X is 

X	- 2.5	- 1.5	-0.5	0.5	1.5
P(X)	0.35	0.25	0.2	0.15	0.05

Then the c.d.f. of X is

Options

• X	-2.5	-1.5	-0.5	0.5	1.5
  F(X)	0.35	0.5	0.7	0.75	0.8

• X	-2.5	-1.5	-0.5	0.5	1.5
  F(X)	0.35	0.5	0.7	0.85	1

• X	-2.5	-1.5	-0.5	0.5	1.5
  F(X)	0.35	0.6	0.8	0.85	1

• X	-2.5	-1.5	-0.5	0.5	1.5
  F(X)	0.35	0.6	0.8	0.95	1

Answer 1

X	-2.5	-1.5	-0.5	0.5	1.5
F(X)	0.35	0.6	0.8	0.95	1

Explanation:

F(x₁) = p₁ = 0.35

F(x₂) = p₁ + p₂ = 0.35 + 0.25 = 0.6

F(x₃) = p₁ + p₂ + p₃ = 0.6 + 0.2 = 0.8

F(x₄) = p₁ + p₂ + p₃ + p₄ = 0.8 + 0.15 = 0.95

F(x₅) = p₁ + p₂ + p₃ + p₄ + p₅ = 0.95 + 0.05 = 1