I'm having trouble with grasping cdf's. If I have a cumulative distribution function

F(x) =

.0 ----- x<-2

.2 ----- -2 ≤ x< 0

.5 ----- 0 ≤ x < 1

.7 ----- 1 ≤ x < 3

.9 ----- 3 ≤ x < 4

1.0 ----- x ≥ 4

Im trying to evaluate P(-1 < X < 3) and P(X=4). For P(-1 < X < 3) im doing P(3≤ X<4)-P(-2≤ X<0) which gives me .7. For P(X=4) I subtract P(3<=X<4) from 1 giving me 1-.9=.10.

Im not sure I am doing this right though.

F(x) =

.0 ----- x<-2

.2 ----- -2 ≤ x< 0

.5 ----- 0 ≤ x < 1

.7 ----- 1 ≤ x < 3

.9 ----- 3 ≤ x < 4

1.0 ----- x ≥ 4

Im trying to evaluate P(-1 < X < 3) and P(X=4). For P(-1 < X < 3) im doing P(3≤ X<4)-P(-2≤ X<0) which gives me .7. For P(X=4) I subtract P(3<=X<4) from 1 giving me 1-.9=.10.

Im not sure I am doing this right though.

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